AP Statistics · Key concepts

The AP Stats cheat sheet: every concept the exam keeps coming back to.

Q: Which AP Stats units carry the most exam weight?

Inference (Units 6-9, especially proportions and means) carries roughly 40% of the exam and feeds the investigative task. Drill the inference template before any other content.

Q: How do I stop losing points on the investigative task?

Save 25 minutes for it. Use the standard structure: identify the method, check conditions, compute, conclude in context. Skipping the conditions step is the most common cap.

Q: How important is calculator notation in AP Stats?

Don't write only calculator syntax (e.g., '2-PropZTest(...)'). The rubric requires you to name the procedure, show the formula or relevant values, and write the conclusion in plain English.

Data analysis · Probability & sampling · Inference & communication — what the rubric is really testing.

days until your AP Stats exam

Thu, May 7 · Afternoon session

the whole cheat sheet

Data

Data analysis

Units 1-2

Center, spread, shape, outliers

Always describe all four when summarizing a distribution.

Boxplots & histograms

Compare distributions side-by-side using shape, center, spread, outliers.

Correlation vs. causation

Only experiments allow causal claims. r tells you nothing about cause.

Linear regression

ŷ = a + bx. Interpret slope in context. Check residual plot for fit.

Random

Probability & sampling

Units 3-5

Sampling methods & bias

SRS, stratified, cluster — name a real bias source for each non-random method.

Conditional probability

P(A|B) = P(A∩B)/P(B). Use a two-way table when stuck.

Central Limit Theorem

Sample means follow Normal distribution if n ≥ 30 — even when population isn't Normal.

Sampling distributions

Standard deviation of sample mean = σ/√n. Bigger n shrinks variability.

Inference

Inference & communication

Units 6-9

Hypothesis test structure

State H₀, Hₐ; check conditions; compute; conclude in context.

Check conditions BEFORE computing

Random, 10%, success-failure (or large counts) — name them all.

Confidence intervals

'We are 95% confident the true mean is between X and Y.' Wording is rubric-graded.

Type I & Type II errors

Type I = reject true H₀. Type II = fail to reject false H₀. Know both consequences.

Exam at a glance · 3 hours

40 MCQs · 90 min

Slow on conditions/assumptions.

5 Short FRQs · 65 min

~13 min, clear stat communication.

Investigative Task · 25 min

Largest single FRQ — save time.

FRQs = 50% · of score

Investigative task is heaviest.

What AP Stats readers actually reward

Three FRQ habits that separate students who 'get the math right' from students who score it.

Rubric move

Conditions before mechanics

Inference FRQs require explicit checks of conditions BEFORE any computation. Skipping this is the most common 4-essay cap.

Weak

z = 1.85, p = 0.064.

Scoring-ready

Conditions: sample is random ✓, n=200 < 10% of population ✓, np=40 and n(1-p)=160 both ≥ 10 ✓. z = 1.85, p = 0.064.

Rubric move

Conclude in context

A bare numerical conclusion loses points. The conclusion must reference the original problem variables.

Weak

We reject H₀ at α = 0.05.

Scoring-ready

We reject H₀; there is convincing evidence (p = 0.012) that the average commute time exceeds 30 minutes for this city's workers.

Rubric move

Interpret intervals correctly

CI interpretation has tight rubric language. 'Probability the true mean is in this interval' is wrong. 'Confident' is right.

Weak

There is a 95% probability the true mean is between 12 and 18.

Scoring-ready

We are 95% confident that the interval from 12 to 18 captures the true mean number of weekly screen-time hours for this population.

Want to see exactly which FRQ row you're losing points on?

Spot the concept

These are the concepts behind a real AP Stats stem.

Three mini MCQs from the exam's most common skill areas. Tap to reveal the answer.

Which sampling method best supports generalizing results to a population?

AVoluntary response - posting a link online and collecting responses
BConvenience - sampling people entering the first store you pass
CSimple random sample of the full population
DQuota sample from one neighborhood

A population has mean μ = 50 and standard deviation σ = 10. A simple random sample of n = 100 is drawn. What is the approximate distribution of the sample mean?

ANormal with mean 50 and standard deviation 10
BNormal with mean 50 and standard deviation 1
CNormal with mean 5 and standard deviation 1
DUniform with mean 50

A 95% confidence interval for a population proportion is (0.52, 0.68). Which statement is the most accurate interpretation?

AThere is a 95% probability that the true proportion is between 0.52 and 0.68.
B95% of samples will produce intervals that contain the true proportion, and this interval is one such construction.
C95% of the population falls in this interval.
DThe sample proportion is 0.60 with a margin of error of 0.10.

Will you score the 5?

Write one timed FRQ. See exactly where rubric points would slip — while there's still time to fix it.

See the AP Stats subject guide →

Quick questions

Inference (Units 6-9, especially proportions and means) carries roughly 40% of the exam and feeds the investigative task. Drill the inference template before any other content.

Save 25 minutes for it. Use the standard structure: identify the method, check conditions, compute, conclude in context. Skipping the conditions step is the most common cap.

Don't write only calculator syntax (e.g., '2-PropZTest(...)'). The rubric requires you to name the procedure, show the formula or relevant values, and write the conclusion in plain English.

where the 5 starts

40 MCQs. 6 FRQs. The 5 lives in the conditions and conclusion.

Or if you want a schedule.