AP Statistics Study Guide
All 5 units of the AP Statistics course, with the topics College Board lists for each and a short summary of what the unit covers.
Units at a glance
Weightings are College Board's ranges for the multiple-choice section.
Unit 1: Exploring One-Variable Data and Collecting Data
20-30% of the multiple-choice section
The course opens with writing investigative questions that data can answer and defining categorical and quantitative variables. You build tables and graphs for one variable, calculate summary statistics, and describe and compare distributions. You then study random sampling, problems that can occur in sampling, and experimental design, including why random selection matters for generalizing to a population and why well-designed experiments can give evidence that a treatment caused an effect.
Topics in this unit
- Introducing Statistics: What Can We Learn from Data?
- Variables
- Tabular Representation and Summary Statistics for One Categorical Variable
- Graphical Representations for One Categorical Variable
- Graphical Representations for One Quantitative Variable
- Descriptions for One Quantitative Variable Distributions
- Summary Statistics for One Quantitative Variable
- Graphical Representations of Summary Statistics for One Quantitative Variable
- Comparisons of the Distributions for One Quantitative Variable
- The Investigative Question Revisited and Data Collection
- Random Sampling
- Potential Problems with Sampling
- Experimental Design
Shaky on any of these? Paste your class notes for Unit 1 into the free flashcard maker or the free quiz maker.
Unit 2: Probability, Random Variables, and Probability Distributions
15-25% of the multiple-choice section
This unit starts with tables and graphs of two categorical variables and uses them, along with simulation, to build the rules of probability, including mutually exclusive events, conditional probability, and independence. You then calculate and interpret parameters of random variables and work with the binomial distribution and the normal distribution. It ends with sampling distributions and the central limit theorem.
Topics in this unit
- Tabular and Graphical Representations for the Distributions of Two Categorical Variables
- Summary Statistics for Two Categorical Variables
- Estimating Probabilities Using Simulation
- Introduction to Probability
- Mutually Exclusive Events
- Conditional Probability
- Independent Events and Unions of Events
- Introduction to Random Variables and Probability Distributions
- Parameters of Random Variables
- The Binomial Distribution
- The Normal Distribution
- Sampling Distributions and the Central Limit Theorem
Shaky on any of these? Paste your class notes for Unit 2 into the free flashcard maker or the free quiz maker.
Unit 3: Inference for Categorical Data: Proportions
15-25% of the multiple-choice section
This unit introduces sampling distributions and statistical inference for categorical data. When conditions are met, you construct and interpret confidence intervals and carry out significance tests for one population proportion and for the difference between two proportions, and you interpret the two types of errors a test can make. It also covers chi-square tests for homogeneity and independence, which measure how far observed counts are from expected counts.
Topics in this unit
- Estimators
- Sampling Distributions for Sample Proportions
- Constructing a Confidence Interval for a Population Proportion
- Justifying a Claim Based on a Confidence Interval for a Population Proportion
- Setting Up a Test for a Population Proportion
- p-Values
- Carrying Out a Test for a Population Proportion
- Potential Errors When Performing Tests
- Sampling Distributions for the Difference Between Sample Proportions
- Constructing a Confidence Interval for the Difference Between Two Population Proportions
- Justifying a Claim Based on a Confidence Interval for the Difference Between Two Population Proportions
- Setting Up a Test for the Difference Between Two Population Proportions
- Carrying Out a Test for the Difference Between Two Population Proportions
- Setting Up a Chi-Square Test for Homogeneity or Independence
- Carrying Out a Chi-Square Test for Homogeneity or Independence
Shaky on any of these? Paste your class notes for Unit 3 into the free flashcard maker or the free quiz maker.
Unit 4: Inference for Quantitative Data: Means
10-20% of the multiple-choice section
This unit applies inference to quantitative data about population means. When the population standard deviation is unknown, you use t-intervals and t-tests, based on a t-distribution that depends on sample size and has more area in its tails than a normal distribution. You build confidence intervals and run tests for a population mean, a mean difference, and the difference between two population means.
Topics in this unit
- Sampling Distributions for Sample Means
- Constructing a Confidence Interval for a Population Mean or Population Mean Difference
- Justifying a Claim Based on a Confidence Interval for a Population Mean or Population Mean Difference
- Setting Up a Test for a Population Mean or Population Mean Difference
- Carrying Out a Test for a Population Mean or Population Mean Difference
- Sampling Distributions for the Difference Between Two Sample Means
- Constructing a Confidence Interval for the Difference Between Two Population Means
- Justifying a Claim Based on a Confidence Interval for the Difference Between Two Population Means
- Setting Up a Test for the Difference Between Two Population Means
- Carrying Out a Test for the Difference Between Two Population Means
Shaky on any of these? Paste your class notes for Unit 4 into the free flashcard maker or the free quiz maker.
Unit 5: Regression Analysis
10-20% of the multiple-choice section
This unit looks at relationships between two quantitative variables. You describe the form, direction, strength, and unusual features of an association, interpret correlation, and use a linear model to predict the response variable from the explanatory variable. You also interpret the least-squares regression line in context and analyze residuals and departures from a linear pattern.
Topics in this unit
- Graphical Representations Between Two Quantitative Variables
- Correlation
- Linear Regression Models
- Residuals
- Least-Squares Regression
Shaky on any of these? Paste your class notes for Unit 5 into the free flashcard maker or the free quiz maker.
Check where you stand
Took a practice exam? Enter your section scores to see how they add up.
AP Stats study guide FAQ
What units are on the AP Statistics exam?
Which AP Statistics unit counts the most on the exam?
How should I use this AP Stats study guide?
When is the 2027 AP Statistics exam?
Source
Unit titles, weightings and topics are from College Board's AP Statistics Course and Exam Description (Fall 2026). The unit summaries are ours. All AP study guides and score calculators.