AP Stats Stats: Key Skills Assessed 2

Question 1

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?

Accepted Answer

Median

Answer

The median is resistant to skewness and outliers, making it the better measure of center for skewed distributions.

Question 2

When constructing a 95% confidence interval for a population mean, which of the following changes would decrease the margin of error?

Accepted Answer

Increasing the sample size

Answer

A larger sample size reduces the standard error, which decreases the margin of error.

Question 3

A z-score of −2.1 for an observation means that the observation is:

Accepted Answer

2.1 standard deviations below the mean

Answer

A z-score measures how many standard deviations an observation is from the mean; negative means below.

Question 4

In a two-sample t-test comparing group means, which condition is required for the test to be valid?

Accepted Answer

The two samples must be independent of each other

Answer

Independence of the two samples is a required condition for a two-sample t-test.

Question 5

A scatterplot shows a curved, nonlinear relationship between x and y. Which action is most appropriate before performing linear regression?

Accepted Answer

Apply a transformation such as log(y) or √y

Answer

Applying a transformation can linearize a curved relationship so that linear regression is appropriate.

AP Practice Test

AP Practice Test

AP Stats Stats: Key Skills Assessed 2