Stats: Key Skills Assessed Flashcards
7 cards from real AP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Stats: Key Skills Assessed flashcards as text
A researcher collects data on reaction times (ms) for 50 subjects. The distribution is strongly right-skewed. Which measure of center best describes the data?
Answer: Median
The median is resistant to skewness and outliers, making it the better measure of center for skewed distributions.
When constructing a 95% confidence interval for a population mean, which of the following changes would decrease the margin of error?
Answer: Increasing the sample size
A larger sample size reduces the standard error, which decreases the margin of error.
A z-score of −2.1 for an observation means that the observation is:
Answer: 2.1 standard deviations below the mean
A z-score measures how many standard deviations an observation is from the mean; negative means below.
In a two-sample t-test comparing group means, which condition is required for the test to be valid?
Answer: The two samples must be independent of each other
Independence of the two samples is a required condition for a two-sample t-test.
A scatterplot shows a curved, nonlinear relationship between x and y. Which action is most appropriate before performing linear regression?
Answer: Apply a transformation such as log(y) or √y
Applying a transformation can linearize a curved relationship so that linear regression is appropriate.
A Type I error in hypothesis testing occurs when:
Answer: The null hypothesis is true and we reject it
A Type I error is rejecting a true null hypothesis, also called a false positive.
Which of the following best describes the power of a hypothesis test?
Answer: The probability of rejecting the null hypothesis when it is false
Power is the probability of correctly rejecting a false null hypothesis; it equals 1 − β.