# Sports Business Analytics with ChatGPT Code Interpreter - Beginner Level

In this introductory course, we will leverage ChatGPT and natural language prompting to perform key business analytics techniques on sports data, including descriptive/inferential statistics, regression modeling, ANOVA, and statistical comparisons. Through blended explanations and hands-on demonstrations, you will build a practical toolkit to extract insights from sports metrics and drive data-informed decisions, no coding or statistics background required.

###### Descriptive Statistics

Descriptive Statistics is a branch of statistics that deals with the summarization and representation of data. In the vast realm of data analysis, it provides a powerful way to understand the key characteristics of a dataset at a glance. It's a starting point that guides further analysis.

Descriptive Statistics is split into two main types: Measures of Central Tendency and Measures of Dispersion. Measures of Central Tendency help us identify the center point or the typical value of a dataset. They include the Mean (average), Median (middle value), and Mode (most frequent value).

Measures of Dispersion, on the other hand, help us understand the spread or variability within our data. They include the Range (difference between the maximum and minimum values), Variance (average of the squared differences from the Mean), and Standard Deviation (square root of the Variance).For this course, be sure to download the “sales_data_20230720.csv” dataset: Download File

###### Understanding Measures of Central Tendency

Mean:  The arithmetic average of a set of values. To calculate the mean, you sum up all the values and divide by the number of values. The mean gives you a sense of the "center" of the data.

Median: The middle value when a dataset is sorted in ascending or descending order. It's the point that splits the data into two equal halves. The median is useful when there are outliers that skew the mean.

Mode: The value that appears most frequently in a dataset. There can be multiple modes if more than one value has the highest frequency. The mode would tell you the most common sales amount in the data.

###### Prompt: Applying Measures of Central Tendency

Using the dataset 'sales_data_20230720.csv', compute the mean, median, and mode for Total_Sales, Units_Sold, and Profit. Show the results in formatted text and formatted table view.  Provide a link to downloadable versions of the table.

Total Sales:

• ‍The mean is 5,254.837
• The median is 5,406.529
• The mode is 1,087.194
Units Sold:
• The mean is 103.790
• The median is 105.500
• The mode is 141.000
Profit:
• The mean is 567.839
• The median is 550.725
• The mode is 117.371
###### Interpretation of Measures of Central Tendency

Prompt:  “Provide a detailed interpretation of these statistics.”

Total Sales:

• The mean value is 5,254.837, which indicates that, on average, the total sales amount per transaction is around 5,254.837 units.
• The median value is 5,406.529, which is the middle point of total sales when arranged in ascending order. This means that half of the sales amounts are above 5,406.529 units, and half are below.
• The mode value is 1,087.194, which is the most frequently occurring sales amount in the dataset. This suggests that many transactions result in a total sales amount of around 1,087.194 units.
Units Sold:
• The mean value is 103.790, indicating that on average, around 104 units are sold per transaction.
• The median value is 105.500, meaning that in the middle of the dataset when sorted, around 105 units are being sold.
• The mode value is 141.000, which is the most common number of units sold in a transaction.
Profit:
• The mean profit value is 567.839, which means that the average profit per transaction is around 567.839 units.
• The median profit is 550.725, implying that half of the transactions yield a profit greater than 550.725 units, and half yield less.
• The mode value of profit is 117.371, which is the profit that occurs most frequently in the dataset.

Now let’s test for Measures of Dispersion such as Range, Variance, and Standard Deviation.  The Range provides the span of our sales data, the Variance tells us how much the sales data tends to deviate from the mean, and the Standard Deviation is a measure of the amount of variation or dispersion in the sales values.

###### Understanding Measures of Dispersion

Range: The range is the simplest measure of dispersion. It is calculated as the difference between the maximum and minimum values in the dataset. The range gives a sense of the span of your data. However, it is highly sensitive to outliers or extreme values. A single very large or very small value can greatly impact the range, potentially giving a misleading picture of the data's dispersion.

Variance: Variance measures how much the data deviates from the mean, on average. It is calculated by taking the average of the squared differences from the mean. Variance can be a useful measure of spread because it takes into account all data points. However, because it uses squared differences, its units are the square of the original units (for example, if your data is in dollars, variance would be in square dollars), which can make interpretation less intuitive.

Standard Deviation: The standard deviation is the square root of the variance. It measures the average distance between each data point and the mean. Because it uses the same units as the original data, it is generally more interpretable than variance. A small standard deviation indicates that the data points tend to be close to the mean, while a large standard deviation indicates that the data points are spread out over a wider range.

These measures of dispersion can give us a more nuanced understanding of our data beyond the central tendency measures (mean, median, mode). By telling us about the spread of our data, they provide important context that can help us make more informed decisions based on our data.

###### Prompt: Applying Measures of Dispersion

Using the dataset 'sales_data_20230720.csv', compute the measures of dispersion, including the range, variance, and standard deviation, for Total_Sales, Units_Sold, and Profit. Show the results in formatted text and formatted table view.  Provide a link to downloadable versions of the table.

Total Sales:
• The range is 8,844.67, indicating that the span of sales data is 8,844.67 units.
• The variance is 6,617,922.14, suggesting a significant dispersion or variability in the total sales.
• The standard deviation is 2,572.53, meaning on average, total sales deviate from the mean by about 2,572.53 units.
Units Sold:
• The range is 178.00, so the number of units sold varies across a range of 178 units.
• The variance is 2,597.82, indicating a substantial variability in the number of units sold.
• The standard deviation is 50.97, which means that the number of units sold typically deviates from the average by about 51 units.
Profit:
• The range is 866.11, suggesting that profits span a range of 866.11 units.
• The variance is 67,851.49, indicating a high variability in profits.
• The standard deviation is 260.48, meaning that profits typically deviate from the mean by about 260.48 units.
###### Interpretation of Measures of Dispersion

Prompt:  “Provide a detailed interpretation of these statistics.”

Total Sales:

• The range is 8,844.67 units, which means that the total sales vary across a fairly wide range. This suggests a significant diversity in the transaction sizes.
• The variance is quite high at 6,617,922.14. Since variance measures how much the data deviates from the mean, this high variance suggests that there is a large spread in the total sales amounts. Some sales amounts are far from the mean, indicating significant variability in the transaction sizes.
• The standard deviation is 2,572.53 units. This means that, on average, total sales amounts deviate from the mean by about 2,572.53 units. This further underscores the variability in the transaction sizes.
Units Sold:
• The range is 178 units, indicating that the number of units sold per transaction varies across a considerable range. This could be due to variations in customer demand, differences in product types, etc.
• The variance is 2,597.82, which is quite high, suggesting that there's a significant spread in the number of units sold per transaction.
• The standard deviation is 50.97 units. This means that, on average, the number of units sold per transaction deviates from the mean by about 51 units. This further confirms the substantial variability in the number of units sold per transaction.
Profit:
• The range is 866.11 units, indicating that profits span a wide range. This suggests significant variability in the profitability of transactions, which could be due to factors like differences in product types, variations in units sold, etc.
• The variance is 67,851.49, which is quite high, suggesting a significant spread in profits. Some profits are far from the mean, indicating significant variability in the profitability of transactions.
• The standard deviation is 260.48 units, which means that, on average, profits deviate from the mean by about 260.48 units. This further confirms the substantial variability in the profitability of transactions.
###### In This Module

We've been able to gain insights into our sales data. The mean, median, and mode helped us understand the "typical" values in our data, while the range, variance, and standard deviation gave us a sense of how much our data varies. These insights can help us make informed decisions and forecasts about future sales.

That's it for this part of the course. Remember, understanding your data is the first step to making informed decisions in the business of sports. Keep practicing these techniques, and don't hesitate to experiment with different prompts with the ChatGPT Code Interpreter.

###### Data Visualization

Welcome back to our Sports Business Analytics course, facilitated by ChatGPT Code Interpreter. Having explored the foundational concepts of Descriptive Statistics in our previous session, we're now ready to embark on an exciting journey into the realm of Data Visualization.

Data visualization is a cornerstone of sports business analytics. It distills complex datasets into visually engaging and easily digestible formats, unveiling valuable insights that might otherwise remain hidden in raw data. Throughout this part of the course, we'll leverage a newly introduced dataset from the sports sector. By creating compelling visuals such as charts and graphs, we'll reveal the stories our data is eager to tell.

###### Understanding Data Visualization

Highlight Trends and Patterns:  Charts like line graphs can showcase trends over time, allowing analysts to quickly spot rises, falls, and anomalies. Bar and column charts visualize comparisons and rankings. Scatter plots reveal relationships and correlations between variables. These common charts highlight trends and patterns in data.

Compare Categories and Parts of a Whole: Pie charts, donut charts, and tree-maps break down data into categorical parts and allow easy comparison between those categories. The parts integrate to form a whole, giving perspective on the composition of data.

Represent Geospatial Data: Maps visualize data with a geographic component. They allow analysts to spot regional patterns and variances. Heat maps use color coding to represent concentrations and intensities of data across locations.

Track Performance Over Time: Time series visualizations like line charts depict how metrics change over time. Analysts can analyze performance historically and forecast into the future based on trends.

For this course, we will demonstrate two common data visualizations using the dataset “american_soccer_data_with_year.csv” available here: [LINK]. This dataset contains soccer data with a year variable added.

While we will only cover two common charts in this course section, the ChatGPT Code Interpreter makes it easy to experiment with different types of visualizations for various data types. Feel free to prompt the interpreter to generate additional visualizations to further analyze this dataset.

However, it's important to note that all AI systems, including ChatGPT, have a tendency to "hallucinate" or generate plausible but incorrect or meaningless outputs. Here is a helpful blog post on ChatGPT's hallucination tendencies and ways to detect and avoid them: [LINK]. When exploring new visualizations, be sure to validate that the outputs make sense for the given data.

The core skills covered in this course section provide a strong foundation. With thoughtful prompting and validation, the ChatGPT Code Interpreter can be a powerful tool for gaining additional insights through data visualization. But a critical eye is key to ensuring meaningful, accurate charts and graphs.

###### Prompt: Applying Measures for Data Visualization

Using the dataset 'american_football_data_with_year.csv', create a bar chart to show the average 'Goals Scored' by each team. Display the bar chart on the screen. Using the dataset 'american_football_data_with_year.csv', create a boxplot to show the distribution of 'Goals Scored' by each of the top 5 teams with the most records. Display the boxplot on the screen. ###### Interpretation of Data Visualization Results

Prompt:  “Provide a detailed interpretation of these statistics.”

Bar Chart of Average Goals Scored by Team: This bar chart shows the average number of goals scored by each team. From the plot, we can see that some teams have a higher average of goals scored than others.

Boxplot of Goals Scored by Team: The boxplot shows the distribution of 'Goals Scored' by each of the top 5 teams with the most records. Each box represents the interquartile range (IQR, the range between the 25th percentile and the 75th percentile) of goals scored by a team, with the line inside the box being the median. The whiskers extend to the minimum and maximum values within 1.5 times the IQR from the box, and points outside the whiskers are considered outliers. From the plot, we can compare the distributions of goals scored among the top 5 teams. For example, a team with a higher median and a larger IQR might have a more varied performance in scoring goals, while a team with a lower median and a smaller IQR might have a more consistent performance.

###### In This Module

We dove into the world of data visualization and its integral role in sports business analytics. We covered core concepts like using charts, graphs, and plots to uncover hidden insights from complex data.

Specifically, we gained hands-on practice creating visualizations like bar charts and box plots using a sample soccer dataset. Interpreting these visuals enabled us to analyze distribution, find averages, identify relationships, and compare distributions for key metrics.

This foundation provides a great springboard to further explore data visualization. I encourage you to experiment more with the dataset and ChatGPT interpreter, trying new prompt phrasings to generate additional impactful visuals. The key is crafting clear, detailed prompts and critically reviewing the outputs.

The art of visualizing data takes practice, but it's an invaluable skill for turning raw datasets into compelling narratives for decision making. Keep honing your data visualization abilities with thoughtful prompting and validation. Feel free to use the interpreter creatively to enhance your learning.

###### Inferential Statistics

In the previous modules, we focused on Descriptive Statistics - summarizing and describing the key characteristics of a dataset. Now we will level up to making inferences and predictions about data based on samples.

Inferential Statistics allows us to draw conclusions and make forecasts beyond the data we have directly observed. It involves using sample data to make generalizations about an entire population.

In this course, we will learn hypothesis testing and confidence intervals. We will follow this with correlation analysis and regression modeling in the next course. Applying these methods correctly enables us to infer significant insights from data samples.

We will use ChatGPT Code Interpreter to perform inferential analyses on new datasets. The interpreter's coding capabilities will bring the statistical concepts to life through hands-on demonstration.

###### Understanding Hypothesis Testing

Hypothesis testing is a core technique in inferential statistics that allows us to make decisions about a population based on a sample. It involves these key steps:

State the Null and Alternative Hypotheses:

• Null Hypothesis (H0): Represents the status quo, stating that there is no significant effect or difference.
• Alternative Hypothesis (Ha): Represents the change, stating that there IS an effect or difference.

Set the Significance Level: The percentage threshold for how much risk we're willing to take in rejecting the null hypothesis incorrectly. Common levels are 5% or 1%.

Calculate the Test Statistic: Compute a test statistic (like a z-score or t-score) using sample data to quantify the likelihood of the result under the null hypothesis.

Determine the p-value: Probability of obtaining a result at least as extreme as the one observed, assuming the null hypothesis is true. Lower p-value → more significant result.

Compare to Significance Level: If the p-value is below the set significance level, we reject the null hypothesis in favor of the alternative. Otherwise, we fail to reject the null hypothesis.

Draw a Conclusion: Rejection of null indicates significant evidence for the alternative hypothesis. Failure to reject means data is insufficient to conclude a difference.

Understanding this process empowers us to make statistically valid inferences about populations based on sample data. I encourage you to gain hands-on experience with hypothesis testing using ChatGPT Code Interpreter beyond what we cover in this course.

###### Understanding Confidence Intervals

In statistics, a confidence interval (CI) is a type of interval estimate that is used to indicate the reliability of an estimate. It is an observed range in which a given percentage of test outcomes fall. We often use confidence intervals to express the degree to which we are confident that a population parameter, such as the mean or standard deviation, falls within a certain range of values.

Imagine we're trying to estimate an unknown parameter, like the average height of all baseball players. We could take a random sample of baseball players, calculate the average height from this sample, and use this sample mean as an estimate of the true population mean. However, because we've only taken a sample, our estimate is likely to be slightly off. A confidence interval gives us a range of values around our sample estimate that we believe the true population parameter falls into.

The width of the confidence interval gives us some idea about how uncertain we are about the unknown parameter. A wide confidence interval may indicate that more data should be collected before anything very definite can be said about the parameter. The confidence level is the probability that the interval estimate will contain the true population parameter. This is usually expressed as a percentage – for example, a 95% confidence interval means that we are 95% confident that the true population parameter falls within the interval.

In practice, you can construct a confidence interval for a population parameter using a variety of methods, depending on the parameter and the data. For a population mean, where the population standard deviation is unknown, the confidence interval is typically calculated from the sample mean and the sample standard deviation, using a t-distribution.

###### In This Module

We explored fundamental concepts in inferential statistics, including hypothesis testing and confidence intervals. These techniques allow us to make data-driven inferences about populations based on samples.

Using a sample dataset, we employed hypothesis testing to evaluate claims by forming hypotheses, determining the significance level, calculating test statistics, finding p-values, and ultimately deciding to reject or fail to reject the null hypothesis. This rigorous scientific approach empowers us to make statistically valid conclusions.

We also learned about confidence intervals - ranges of values we can be confident contain the true population parameter. Understanding confidence levels and interval widths helps us quantify uncertainty in parameter estimates.

Applying these inferential techniques correctly is crucial for sound scientific inquiry and business analytics. Through ChatGPT Code Interpreter demonstrations, we gained hands-on experience bringing statistical concepts to life.

###### Understanding Correlation Analysis

Correlation is a statistical measure that describes the association between random variables. In other words, it's a way of quantifying how strongly related two variables are to each other.

Correlation is defined as the measure of the joint variability of two random variables. It's a way to understand how one variable changes in relation to another. The correlation coefficient, often denoted by r, is a numerical value between -1 and 1 that represents the strength and direction of the linear relationship between variables.

Correlation is essential in statistics because it can suggest a strong relationship between two or more variables. With this relationship, we can predict one variable from the other.

A Positive Correlation occurs when two variables increase or decrease together. For instance, the more time you spend studying for a test, the higher your score is likely to be. The correlation coefficient for a positive correlation will be between 0 and 1.

A Negative Correlation occurs when one variable increases as the other decreases, and vice versa. For example, the more time you spend watching TV, the less time you have to study. The correlation coefficient for a negative correlation will be between -1 and 0.

No Correlation occurs when there's no relationship between the two variables. If one variable changes, it does not predict a similar change in the other variable. In this case, the correlation coefficient is around 0.

The most common method to calculate a correlation coefficient is the Pearson correlation coefficient, which is used to measure the strength and direction of the linear relationship between two variables.

Keep in mind that correlation does not imply causation – even if two variables have a strong correlation, that doesn't mean that changes in one variable cause changes in the other.

###### Prompt: Performing Correlation

The scatter plot visualizes the relationship between age and salary. The points in the plot show a clear upward trend, suggesting a positive correlation between age and salary.

The Pearson correlation coefficient is approximately 0.93, which indicates a strong positive correlation between age and salary.

The p-value is 0.0, which is less than the common significance level of 0.05. Therefore, we reject the null hypothesis and conclude that the correlation between age and salary is statistically significant.

###### Interpretation of Correlation

Prompt: "Based on the results of the correlation analysis between age and salary from the 'employee_dataset.csv' dataset, can you provide a detailed interpretation of the results? Please explain the meaning of the correlation and what it tells us about the relationship between age and salary."

The correlation coefficient is approximately 0.93. This value is very close to 1, which indicates a strong positive correlation. In the context of this dataset, a positive correlation means that as age increases, salary also tends to increase, and vice versa. The strength of this correlation suggests that age and salary are closely related in this dataset.

The scatter plot visually confirms this positive correlation, as we can see a clear upward trend in the points: as we move right along the age axis (indicating increasing age), we also tend to move up along the salary axis (indicating increasing salary).

However, it's crucial to remember that correlation does not imply causation. While our analysis suggests that age and salary are strongly correlated, it does not mean that simply increasing an employee's age will directly increase their salary. The observed correlation could be influenced by other factors not considered in this analysis, such as job position, years of experience, or education level.

###### In This Module

We explored the important concept of correlation analysis. Correlation quantifies the strength and direction of the relationship between two variables.

Using sample employee data, we calculated the Pearson correlation coefficient between age and salary. We found a strong, statistically significant positive correlation, indicating that age and salary tend to increase together in this dataset.

Through this hands-on demonstration of correlation analysis with ChatGPT Code Interpreter, we gained key skills in quantifying variable relationships, visualizing correlations, performing significance testing, and interpreting results. But we must be careful not to assume correlation implies causation without further investigation.

###### Understanding Regression Analysis

Regression analysis is a form of predictive modeling technique that investigates the relationship between a dependent (target) and independent variable(s) (predictor). This technique is used for forecasting, time series modeling, and finding the causal effect relationship between the variables. It includes many techniques for modeling and analyzing several variables when the focus is on the relationship between a dependent variable and one or more independent variables.

Regression analysis is widely used for prediction and forecasting, where its use has substantial overlap with the field of machine learning. It's also used to understand which among the independent variables are related to the dependent variable, and to explore the forms of these relationships.

In simple linear regression, we predict the output/dependent variable based on one independent variable. The relationship is established based on the linearity assumption between input and output. The line of best fit is found using the method of least squares that minimizes the sum of the squared differences between the observed and predicted values.

Multiple Linear Regression is an extension of simple linear regression used to predict the output based on two or more independent variables. The purpose of multiple linear regression is to model the linear relationship between your independent (explanatory) variables and dependent (response) variables.

###### Prompt: Performing Regression Analysis

Using the 'employee_dataset.csv' dataset, perform a simple linear regression analysis with 'Age' and 'Salary' and then provide a summary of the model."
The Pearson correlation coefficient is approximately 0.93, which indicates a strong positive correlation between age and salary.

For a multiple regression analysis, you might ask:

Prompt:  "Using the 'employee_dataset.csv' dataset, perform a multiple linear regression analysis with 'Age', 'Experience', 'Job Satisfaction’ and 'Salary'. Provide a summary of the model.”

###### Interpretation of Simple Linear Regression

Prompt: "Based on the results of the simple linear regression analysis from the 'employee_dataset.csv' dataset, where 'Age' and 'Salary' were the variables, could you provide a detailed interpretation of the results? Please explain the meaning and what it tells us about the relationship between age and salary."

The coefficient for Age is 3495.37, which means that for each additional year of age, we can expect the salary to increase by approximately \$3495, assuming all other factors remain constant.

The constant (also known as the y-intercept) is 51320. This can be interpreted as the expected salary for an employee of 0 years old, which doesn't make much sense in this context, but mathematically that's what it represents.

The R-squared value is 0.873, which means that approximately 87.3% of the variability in Salary can be explained by Age. This is a high R-squared value, indicating a strong fit to our data.

The p-value for the Age coefficient is 0.000, which is less than 0.05, indicating that the Age variable is statistically significant at the 5% level.

Remember, the interpretation of the regression coefficients assumes all other factors remain constant, and it does not imply causation. Even though age and salary are correlated, it does not mean that increasing an employee's age will directly increase their salary.

###### Interpretation of Multiple Regression Analysis

Prompt: "Based on the results of the multiple linear regression analysis from the 'employee_dataset.csv' dataset, where 'Age', 'Experience', 'Job Satisfaction' and 'Salary' were the variables, could you provide a detailed interpretation of the results and what it tells us about the relationship between these variables."

The coefficients for Age and Experience are 1017.44 and 5012.10, respectively. This means that for each additional year of age, we can expect the salary to increase by approximately \$1017, assuming all other factors remain constant. Similarly, for each additional year of experience, we can expect the salary to increase by approximately \$5012, assuming all other factors remain constant.

The coefficient for Job Satisfaction is 65.29, but the p-value is 0.228, which is greater than 0.05. This indicates that Job Satisfaction is not statistically significant at the 5% level in predicting Salary, assuming other factors remain constant.

The constant (also known as the y-intercept) is 48730. This can be interpreted as the expected salary for an employee of 0 years old, with 0 years of experience and 0 job satisfaction, which doesn't make much sense in this context, but mathematically that's what it represents.

The R-squared value is 0.989, which means that approximately 98.9% of the variability in Salary can be explained by Age, Experience, and Job Satisfaction. This is a very high R-squared value, indicating a strong fit to our data.

Remember, the interpretation of the regression coefficients assumes all other factors remain constant, and it does not imply causation. Even though age, experience, and job satisfaction are related to salary, it does not mean that changing these factors will directly increase the salary. Other factors may be influencing the salary as well.

###### In This Module

We gained hands-on experience with regression analysis using ChatGPT Code Interpreter. Regression is a crucial technique for modeling relationships between variables.We performed simple linear regression to predict salary based on age, and multiple regression with age, experience, and job satisfaction as predictors of salary. The interpreter outputs key metrics like coefficients, p-values, and R-squared that quantify the relationships.

Interpreting the results, we found strong positive correlations between salary and both age and experience. However, job satisfaction was not a statistically significant predictor in the multiple regression model. The high R-squared values indicated the models explained a large portion of salary variability.

However, it's important to note that correlation does not imply causation. The relationships observed may be influenced by confounding factors. Through thoughtful interpretation and inclusion of potential predictors, regression helps reveal associations in data - but further investigation is needed to establish causal mechanisms.

###### t-Tests

‍t-tests are statistical tests used to determine if there is a significant difference between the means of two groups. They are very commonly used in scientific research to test hypotheses and support conclusions. In this blog post, we'll cover the basics of t-tests and walk through a few examples of the most common types:

• One-Sample t-Test: Compares the mean of a sample to a known population mean
• Independent Two-Sample t-Test: Compares the means of two unrelated groups
• Paired Sample t-Test: Compares means of two related groups, often before/after scenarios

‍Understanding when to use each type of t-test is important for drawing accurate inferences from your data. We'll look at the assumptions required for each test and how to interpret the results.

###### Understanding t-Test

One-Sample t-Test:  The one-sample t-test is used when you want to know if your sample mean differs significantly from a population mean. For example, suppose you're a sports coach and want to know if the average speed of your team significantly differs from the league average. In this case, you could use a one-sample t-test.

Independent Two-Sample t-Test:  An independent two-sample t-test is used to compare the means of two independent groups. Let's say you are investigating whether the average goal score differs significantly between two football teams. The two teams are independent groups, and you can use an independent two-sample t-test to test your hypothesis.

Paired Sample t-Test:  The paired sample t-test, also known as the dependent sample or paired t-test, is used when the samples are dependent; that is, the same entity has been measured twice. This scenario can occur when we measure something before and after a certain event or intervention. For instance, you might want to test if a training program has significantly improved the fitness levels of your athletes by conducting fitness tests before and after the program.

###### Prompt: Performing t-Tests

One-Sample t-Test:  "Using the data from the 'football_data.csv' file, perform a one-sample t-test to determine if the average speed of our team differs significantly from the league average. Assume that the column representing the team's speed is labeled as 'Team_Speed' and the league average speed is represented as a given value, say 'League_Avg_Speed'. Please show the t-statistics and p-value from the test."

For this part of the course we will be using 'football_data.csv' for the analysis

Independent Two-Sample t-Test:  "Using the data from two separate '.csv' files, 'team1_data.csv' and 'team2_data.csv', perform an independent samples t-test to determine if there is a significant difference in the average speeds of two different teams. Assume that the column representing the teams' speeds is labeled 'Team_Speed' in both files. Please show the t-statistics and p-value from the test."

For this part of the course we will be using ‘team1_data.csv' & 'team2_data.csv’ data sets for the analysis

Paired Sample t-Test:  "Using the data from the 'before_after_training.csv' file, perform a paired samples t-test to determine if there is a significant difference in the average speed of our team before and after a specific training program. Assume that the columns representing the team's speed before and after the training are labeled 'Speed_Before' and 'Speed_After', respectively. Please show the t-statistics and p-value from the test."

For this part of the course we will be using ‘before_after_training.csv’ for the analysis

###### Interpretation of a One Sample t-Test

The results of the one-sample t-test are as follows:

- t-statistic: \ (-5.33)
- p-value: \ (6.11 \ times 10^{-7})

The negative t-statistic indicates that our team's average speed is less than the league average speed.

The p-value is much less than 0.05 (a commonly used significance level), which means we can reject the null hypothesis that the team's average speed is equal to the league's average speed. In other words, there is a statistically significant difference between our team's average speed and the league average speed, with our team having a lower average speed.

For this part of the course we will be using ‘before_after_training.csv’ for the analysis.

###### Interpretation of Independent Samples t-Test

The results of the independent samples t-test are as follows:

- t-statistic: \ (-4.29)
- p-value: \ (2.84 \ times 10^{-5})

The negative t-statistic indicates that Team 1's average speed is less than Team 2's average speed.

The p-value is much less than 0.05 (a commonly used significance level), which means we can reject the null hypothesis that there's no difference between the teams' average speeds. In other words, there is a statistically significant difference between Team 1's average speed and Team 2's average speed, with Team 2 having a higher average speed.

###### Interpretation of a Paired Samples t-Test

The results of the paired samples t-test are as follows:

- t-statistic: \ (-4.55)
- p-value: \ (1.54 \ times 10^{-5})

The negative t-statistic indicates that our team's average speed after the training is higher than the average speed before the training.

The p-value is much less than 0.05 (a commonly used significance level), which means we can reject the null hypothesis that there's no difference between the team's average speed before and after the training. In other words, there is a statistically significant increase in our team's average speed after the training program.

###### In This Module

We explored t-tests, a fundamental statistical method for comparing means between groups.

We covered one-sample t-tests to compare a sample mean to a known population value, two-sample t-tests to compare two independent groups, and paired sample t-tests for before-after scenarios.

Using sample sports data, ChatGPT Code Interpreter allowed us to demonstrate these techniques hands-on. We evaluated t-statistics and p-values to determine if differences in speed were statistically significant.

Properly applying the right type of t-test and interpreting the results empowers us to quantify differences and draw valid conclusions from data. This supports scientific inquiry and business analytics across industries.

###### Understanding P-Values

In the past few blogs we’ve mentioned p-values as it relates to hypothesis testing and interpreting statistical results. Here is a more detailed description of p-values and how they are used in statistics.

In statistical hypothesis testing, a p-value is the probability of obtaining a result as extreme as, or more extreme than, the observed data, assuming that the null hypothesis is true. The null hypothesis is a statement that says there is no effect or no difference in the population.  (reference - t-Test)

Let's consider a real-world sports example. Suppose you are a sports analyst and you want to know whether a new training program has improved the free throw success rate of a basketball team. The null hypothesis in this case might be that the training program has no effect, i.e., the free throw success rate before and after the program are the same.

After you collect the data (free throw success rates before and after the training), you would run a statistical test (like a paired t-test) to compare the two rates. The output of this test would include a p-value.

If the p-value is small (typically, less than 0.05), then the probability of seeing a difference as large as what you observed, assuming the training program had no effect, is very low. In this case, you would reject the null hypothesis and conclude that the training program did have a significant effect on the free throw success rate.

On the other hand, if the p-value is large (greater than or equal to 0.05), then the observed difference could be quite likely even if the training program had no effect. In this case, you would fail to reject the null hypothesis and conclude that there is not enough evidence to say the training program had a significant effect.

It's important to note that a p-value does not tell us the size of the effect or difference, just whether it is likely to be due to chance. It also doesn't tell us about the practical significance or importance of the effect or difference - a small effect can be statistically significant if the sample size is large enough.

Another crucial point is that a p-value is not the probability that the null hypothesis is true. It's a common misunderstanding to interpret a p-value as such. Rather, it's the probability of observing the data you have (or more extreme), assuming the null hypothesis is true.

In terms of probabilities and probability distributions, the p-value is related to the area under the probability distribution curve of the test statistic. For example, in a t-test, the t-statistic follows a t-distribution. The p-value is the area under the t-distribution curve to the right of the observed t-statistic (for a one-tailed test) or both to the right and left of the observed t-statistic (for a two-tailed test). This area represents the probability of observing a t-statistic as extreme as, or more extreme than, the observed value, assuming the null hypothesis is true.

###### In This Module

In this module, we took a deeper look at p-values - those ubiquitous numbers that indicate statistical significance in hypothesis testing.

We explored how p-values represent the probability of obtaining results at least as extreme as those observed, assuming the null hypothesis is true. Small p-values suggest the null is unlikely and we should reject it in favor of the alternative hypothesis.

However, p-values speak only to statistical significance, not practical importance. And they do not give the probability that the null hypothesis itself is true. Proper interpretation is vital.

Gaining intuition for p-values - how they're calculated from test statistics and distributions, and what they imply - is crucial to applying inferential statistics correctly. Thoughtful use of p-values, rather than blind thresholding, allows us to make informed, nuanced conclusions from data.

###### Understanding ANOVA (Analysis of Variance)

Analysis of Variance (ANOVA) is a statistical method used to test the differences between two or more means. It was developed by the eminent statistician Ronald Fisher. ANOVA compares the variance (or variation) between the data sets to the variance within each particular data set. If the variance between certain groups is significantly greater than the variance within each group, then it is likely that the means also differ.

In the realm of sports analytics, ANOVA can be used in a variety of ways. For instance, you may want to compare the average scores of athletes from different training groups, or you may want to compare the performance of different teams over various seasons. ANOVA allows you to make these comparisons in a statistically rigorous way.

One-Way ANOVA:  The simplest type of ANOVA is a One-Way ANOVA. This method is used when we have one independent variable and one dependent variable. The "one-way" refers to one independent variable (a categorical variable) that has two or more levels. For example, you might use a one-way ANOVA to test the hypothesis that the mean batting averages for batters from different countries (USA, Japan, Dominican Republic) are the same.

One-way ANOVA works by comparing the means of the groups and determining whether the within-group variance is much lower than the between-group variance. If it is, then it's likely that the groups differ significantly from each other.

Like many statistical tests, ANOVA makes several assumptions:

Independence: The observations within each group must be independent. This means that the performance of one player or team doesn't influence the performance of another player or team within the same group.

Normality: The data within each group are assumed to follow a normal distribution. While ANOVA is robust to moderate departures from this assumption, extremely skewed or kurtotic distributions can distort the results.

Homogeneity of variance: ANOVA assumes that the variance within each group is the same. This is known as the assumption of homoscedasticity. If this assumption is violated, it can inflate the Type I error rate (the probability of incorrectly rejecting the null hypothesis).

The dependent variable should be continuous: ANOVA requires a continuous (interval or ratio) dependent variable and a categorical independent variable.It's important to check these assumptions before proceeding with ANOVA, as violations can lead to inaccurate results. However, there are variations and alternatives to ANOVA (like Welch's ANOVA or the Kruskal-Wallis test) that can be used when these assumptions aren't met.

###### Prompt: Performing the One-Way ANOVA

"Using the data from the 'one_way_anova_data.csv' file, perform a One-Way ANOVA to determine if there is a significant difference in the average scores of players from different teams. Assume that the column representing the players' scores is labeled 'Score' and the column representing the teams is labeled 'Team'. Please show the F-statistic, degrees of freedom, and p-value from the test."

For this part of the course we will be using ‘one_way_anova_data.csv’ for the analysis.

The results of the one-way ANOVA are as follows:

- F-statistic: (19.48)
- Degrees of freedom: (2) (between groups), \ (297) (within groups)
- p-value: (1.13 \ times 10^{-8})

The F-statistic is quite large and the p-value is much less than 0.05, which means we can reject the null hypothesis that there's no difference between the teams' average scores. In other words, there is a statistically significant difference in average scores between the three teams.

###### Interpretation of the One-Way ANOVA

The one-way ANOVA test we conducted was designed to examine if there are significant differences in the average scores of players from different teams. In this context, the 'Score' variable represents the performance measure of the players (such as points scored in a season), and the 'Team' variable identifies the team to which each player belongs.

The resulting F-statistic from the test is approximately 19.48. The F-statistic is a measure that compares the amount of systematic variance in the data (i.e., variance due to the teams) to the amount of unsystematic variance (i.e., variance within each team, due to individual differences or error). A larger F-statistic indicates that the between-group variance is high relative to the within-group variance, which suggests a significant effect of the team on player scores.

The degrees of freedom for the test are 2 between groups and 297 within groups. The between-group degrees of freedom correspond to the number of teams minus 1, and the within-group degrees of freedom correspond to the total number of players minus the number of teams.

The p-value obtained from the test is approximately (1.13 \ times 10^{-8}), which is much smaller than the typical significance level of 0.05. This means that if the null hypothesis were true (i.e., if all teams have the same average score), the probability of getting an F-statistic as large as 19.48 or larger is extremely small.

Therefore, we reject the null hypothesis and conclude that there is a significant difference in average scores among the teams.

However, this test does not tell us which specific teams are significantly different from each other. To determine that, we would need to perform a post hoc test, such as Tukey's HSD test.

###### In This Module

We explored ANOVA, a crucial statistical method for comparing means between multiple groups.

Focusing on one-way ANOVA, we used a sample sports dataset to demonstrate comparing average scores across teams. The large F-statistic and highly significant p-value indicated strong evidence of differences in mean scores.

Interpreting the ANOVA results revealed significant variation between teams, but further post-hoc testing is needed to pinpoint which specific teams differ. Still, ANOVA provides a rigorous omnibus test before drilling down.

Applying ANOVA allows us to move beyond simple t-tests to simultaneously compare multiple groups. This strengthens the statistical validity of our conclusions. Proper use of ANOVA and follow-up tests will prove invaluable for sports analytics and research.

We also introduced two new concepts.  The first concept was the “Assumptions of the Test”.  The second concept was the “ANOVA Post-Hoc Test”.  We will cover both these concepts in the next two blogs as they relate to the ANOVA test.

###### Statistical Test Assumptions

When performing an ANOVA (Analysis of Variance) test, or indeed any statistical test, it is crucial to understand and meet the assumptions of the test. Failure to do so can lead to inaccurate results and misleading conclusions. In this blog post, we'll walk through the assumptions of the ANOVA test, why they're important, and how to check them.

###### Four key assumptions made by the ANOVA test

Independence: The observations within each group (or each level of the independent variable) must be independent. This means that the performance or value of one observation does not influence the performance or value of another. In the context of a sports analytics example, where we might be comparing the mean scores of different teams, the performance of one team must not affect the performance of another team.

Normality: The observations within each group should follow a normal distribution. This does not need to be perfect, and ANOVA is quite robust to depart from this assumption. However, severe skewness or the presence of outliers can distort the true group mean and standard deviation, which in turn can influence the ANOVA results.

Homogeneity of Variance: This assumption, also known as homoscedasticity, requires that the variance of the dependent variable is equal across all groups. In other words, the spread of scores around the mean should be similar for all teams. If the variance is higher in one group than in others (heteroscedasticity), it can cause imbalances in the test and affect the accuracy of the results.

The dependent variable should be continuous: ANOVA requires a continuous (interval or ratio) dependent variable, and a categorical independent variable.

###### Checking the Assumptions

Before you perform an ANOVA, it's a good idea to check these assumptions.

Independence can be ensured through proper study design. For example, if you're comparing scores of different teams, you would want to make sure that the teams are not influencing each other's performance (e.g., they're not playing against each other in the games you're analyzing).

Normality can be checked in several ways, including visually using histograms or Q-Q plots, or statistically using tests like the Shapiro-Wilk test. Remember, the normality assumption applies to the residuals (the differences between the observed and predicted values) and not the raw dependent variable itself.

Homogeneity of Variance can be checked using Levene's test or visually using a residual plot. In the plot, you're looking for a "cloud" of points that's roughly rectangular, without any clear pattern or change in spread as you move across the plot.

The continuous nature of the dependent variable can be checked simply by examining the variable itself. In ANOVA, this would usually be some form of measurement or count.

If the assumptions are not met, there are several strategies that might help, including transforming your data or using a different statistical test that does not make the same assumptions, such as the Kruskal-Wallis test for non-normal data.

###### Prompt: To Check The Assumptions

"Using the data from the 'one_way_anova_data.csv' file, perform the necessary steps to check the assumptions of the one-way ANOVA. This includes checking for independence, normality, and homogeneity of variance. For the normality check, please provide a histogram or Q-Q plot and consider using the Shapiro-Wilk test. For the homogeneity of variance check, consider using Levene's test. Interpret the results of these checks and discuss whether the assumptions of ANOVA are met."

This is assumed to be true based on the study design. Each player's score is assumed to be independent of the scores of other players.  Normality: The histogram and Q-Q plot of the scores suggest that the data is approximately normally distributed. The Shapiro-Wilk test, which tests the null hypothesis that the data was drawn from a normal distribution, gives a p-value of 0.84. Since this p-value is greater than 0.05, we fail to reject the null hypothesis and conclude that the data does not significantly deviate from normality.

Homogeneity of Variance: Levene's test is used to test if the variances are equal across all groups. The null hypothesis is that the variances are equal. The Levene's test gives a p-value of 0.26. Since this p-value is greater than 0.05, we fail to reject the null hypothesis and conclude that the variances are not significantly different across the teams.

###### Interpretation of the Assumptions Test

Independence: The assumption of independence states that the observations within each group (or each level of the independent variable) must be independent. This means that the performance or value of one observation does not influence the performance or value of another. In our case, the performance of one player should not affect the performance of another player. This is typically guaranteed by the study design. If the independence assumption is violated, it can lead to inflated type I error rates (i.e., falsely rejecting the null hypothesis).

Normality: The assumption of normality requires that the observations within each group are normally distributed. In the context of ANOVA, this applies to the residuals (i.e., the differences between the observed and predicted values) rather than the dependent variable itself. Our test results suggested that the data does not significantly deviate from a normal distribution. This is important because significant deviations from normality can make our test less reliable. It's worth noting that ANOVA is fairly robust to violations of the normality assumption, particularly as the sample size increases.

Homogeneity of Variance: The assumption of homogeneity of variances, also known as the assumption of homoscedasticity, requires that the variance of the dependent variable is equal across all groups. Our Levene's test results suggest that the variances are not significantly different across the teams. This is important because if this assumption is violated (i.e., if the variances are unequal, or heteroscedastic), it can bias our results, leading to an increased type I error rate for smaller groups and an increased type II error rate (i.e., failing to detect a real effect) for larger groups.

###### In This Module

We explored the critical assumptions made by ANOVA and other statistical tests.

Using the one-way ANOVA as an example, we covered assumptions like independence of observations, normality, and homogeneity of variance. Checking these assumptions on sample sports data revealed no major violations based on visual inspections and statistical tests.

However, this careful checking process is essential before proceeding with any statistical test. Failure to meet key assumptions can undermine the validity of the results. Blindly running ANOVA without verifying assumptions risks inaccurate, misleading conclusions.

###### ANOVA Post Hoc Test

When an ANOVA test finds a significant effect, it means there is a difference somewhere among the group means, but it doesn't tell us exactly where those differences lie. Post hoc tests, also known as multiple comparisons tests, help us pinpoint which specific groups differ from each other. Here are several commonly used post hoc tests:

Tukey's HSD (Honestly Significant Difference) Test: This test compares all possible pairs of means and is one of the most commonly used post hoc tests. Tukey's HSD controls for the familywise error rate and is a good choice when your groups have similar sample sizes and variances.

Bonferroni Correction: This technique involves dividing the critical p-value by the number of comparisons being made. The Bonferroni correction is very strict and reduces the chances of obtaining false-positive results (Type I errors), but it increases the chances of obtaining false-negative results (Type II errors).

Scheffé's Method: This test is more conservative than Tukey's HSD and is appropriate when comparisons are not planned in advance and are based on the data.

Newman-Keuls Test: This test is stepwise and less conservative than both Scheffé's method and Tukey's HSD, meaning it's more likely to find significant differences where they exist.

Fisher's Least Significant Difference (LSD) Test: This method involves performing a separate t-test for each pair of groups. It is the most liberal of the post hoc tests and has the highest risk of Type I errors, so it is generally not recommended when there are many groups.

Games-Howell Test: This test does not assume equal variances and is especially useful when the groups have unequal variances and/or unequal sample sizes.

Choosing the right post hoc test depends on your specific study design and the characteristics of your data. Once you've chosen a test, you can usually perform it using statistical software. The software will compare each pair of group means and adjust the p-values according to the specific post hoc test procedure. You can then use these adjusted p-values to determine which groups significantly differ from each other.

For this course we will not perform the post-hoc test for the ANOVA.

###### In This Module

We explored post hoc tests, which are used after ANOVA to pinpoint specific group differences.

While ANOVA tells us if differences exist somewhere among the means, post hoc tests like Tukey's HSD home in on which pairs of groups significantly differ. These tests adjust p-values to control errors when making multiple comparisons.

Understanding options like Tukey's test, Bonferroni correction, Scheffé's method, and others allows us to choose the right post hoc test for our needs. Using these tools correctly is key to drawing meaningful conclusions from ANOVA results.

Although we did not perform post hoc tests hands-on in this course module, I hope this introduction provides a foundation for applying them yourself. ANOVA followed by thoughtful post hoc analysis can reveal valuable insights into group data.

###### Recap of Beginner Series

This online course provided a comprehensive introduction to sports business analytics using ChatGPT Code Interpreter. We started from the foundations of descriptive statistics and worked our way up to more advanced techniques like ANOVA, regression, and hypothesis testing. The unique blend of conceptual explanations and hands-on demonstrations with real sports data gave us applied skills to extract meaningful insights.

Descriptive Statistics: In the descriptive statistics module, we loaded a sales dataset and calculated measures of central tendency (mean, median, mode) and dispersion (range, variance, standard deviation). This allowed us to understand the distribution, main values, and variability of key metrics like total sales, units sold, and profit. Interpreting these statistics provided a crucial starting point for further analysis.

Data Visualization: Next, we created visualizations like histograms, bar charts, and boxplots on sample soccer data. By representing data visually, we could easily spot patterns, compare values, and analyze distributions. This section emphasized the importance of visualizing data to uncover insights. We also discussed thoughtful prompting of ChatGPT and validating outputs.

Inferential Statistics: Shifting to inferential statistics, we performed hypothesis testing on sample data to make inferences about populations. By setting hypotheses, determining p-values, and evaluating significance, we could statistically test claims. We also learned about confidence intervals to quantify the reliability of estimates. These techniques empowered us to move beyond mere description to draw scientific conclusions.

Correlation and Regression: Building more advanced skills, we calculated correlation coefficients to quantify the strength of relationships between variables like age and salary. Visualizing the correlations and testing their significance, we avoided assuming causation. We then performed regression analysis to model and predict relationships between variables. Regressions on age, experience, and other factors predicted salary levels and explained variability.

Comparing Means: Using t-tests, we compared sample means to known values, between independent groups, and for before-after scenarios. Evaluating t-statistics and p-values enabled statistically sound conclusions about differences in means. Moving to ANOVA, we could simultaneously compare means across multiple groups as an upgrade from t-tests. The ANOVA process, assumptions, and post-hoc tests give rigor to comparisons.

This beginner course equipped us with applied sports business analytics skills using ChatGPT Code Interpreter as an innovative learning tool. We built intuition, hands-on abilities, and analytical thinking to extract insights from data. This foundation sets the stage for more advanced techniques in predictive modeling, forecasting, deep learning, and more as we continue honing our skills.