AP Statistics Chapter 9 Test Flashcards

Study Notes

Hypothesis Testing

A "guilty" finding corresponds to p ≤ α, leading to the rejection of the null hypothesis (Ho), indicating convincing evidence for the alternative hypothesis (Ha).
A "not guilty" finding corresponds to p > α, resulting in failing to reject Ho, signifying a lack of convincing evidence for Ha.

p-value Interpretation

A p-value expresses the probability of observing the sample data (or more extreme) assuming the null hypothesis is true.
It quantifies how likely the observed results could occur purely by chance.

Golf Test Case

Null hypothesis (Ho): The standard deviation of shots with the new 7-iron is 15 yards.
Alternative hypothesis (Ha): The standard deviation of shots with the new 7-iron is less than 15 yards.
Observed sample standard deviation is 13.9 yards from 50 shots.
A p-value of 0.25 indicates there is a 25% chance of observing a standard deviation of 13.9 yards or less if the true standard deviation is indeed 15 yards.

Types of Errors

Type I Error: Convicting an innocent person; finding significant evidence against the null hypothesis when it is true.
Type II Error: Letting a guilty person go free; failing to find significant evidence against the null hypothesis when it is false.

New AAA Battery Case

Null hypothesis (Ho): The mean lifetime of the new batteries is 30 hours.
Alternative hypothesis (Ha): The mean lifetime of the new batteries is greater than 30 hours.
Sample mean lifetime of the new batteries is 33.9 hours from 15 batteries.
The resulting p-value of 0.0729 indicates some evidence, but not strong enough to reject Ho.
Type I Error in this context: Incorrectly concluding that the new batteries last longer than 30 hours when they do not, potentially leading to unnecessary production costs.
Type II Error: Failing to recognize that the new batteries do last longer than 30 hours, which would result in missed opportunities for production.
The seriousness of the error may vary, but a Type I error could lead to financial losses while a Type II error could prevent the introduction of a better product.

Test Statistic Calculation

The calculation for testing proportions uses the 1-PropZTest, where:
- po (hypothesized proportion) = 0.8
- x (number of successes in the sample) = 32
- n (sample size) = 50.

Description

This quiz focuses on key concepts from Chapter 9 of the AP Statistics curriculum, including hypothesis testing and p-values. Each flashcard presents essential definitions and interpretations vital for mastering statistical inference. Enhance your understanding and prepare effectively for your assessments.