Identify Inference Procedure AP Stats

Do the students at a certain university spend more than twenty hours per week on classwork, on average?

• one-sample t test for a mean

• one-sample t interval for a mean

• two-sample t test for the difference of means

• two-sample t interval for the difference of means

Answer explanation

This is a yes/no question that requires a test, not an interval. There is only one population: students at the university.

What percentage of students at a certain university live on campus?

• one-sample z test for a proportion

• one-sample z interval for a proportion

• two-sample z test for the difference of proportions

• two-sample z interval for the difference of proportions

Answer explanation

The question asks for the value of the proportion, so an interval is needed rather than a test. There is only one population: students at the university.

If p₁ - p₂ = 0, is in the 90% confidence interval, what can we conclude at α = 0.10?

• Reject H₀, there is sufficient evidence to conclude H_a

• Reject H₀, there is NOT sufficient evidence to conclude H_a

• Fail to reject H₀, there is sufficient evidence to conclude H_a

• Fail to reject H₀, there is NOT sufficient evidence to conclude H_a

A two-tailed hypothesis test with H₀: μ₁-μ₂ = 0 produced a p-value of 0.08.  Which of the following must be true?

• The 90% confidence interval will NOT contain 0.

• The 95% confidence interval will NOT contain 0.

• The 99% confidence interval will NOT contain 0.

• All the confidence intervals listed will contain 0.

• A

• B

• C

• D

• E

Which of the following is an appropriate interpretation of a p-value?

• The probability of rejecting H₀, when we should have failed to reject H₀.

• The probability of failing to reject H₀, when we should have rejected H₀.

• Assuming H₀ is true, it is the probability of obtaining our sample statistic or a more extreme value.

• Assuming H₀ is NOT true, it is the probability of obtaining our sample statistic or a more extreme value.

An amusement park owner is considering changing her model from "pay for each ride" to "one fee for all rides."  She observes 2000 guests to see if they spend less than the $30 fee that she intends to put into place. Which procedure is appropriate?

• t interval for means

• t test for means

• z interval for proportions

• z test for proportions

Estimate the average number of pinecones that a 30-year-old pine tree produces each year.  Fifty-five pine trees were observed over a one-year period. Which procedure is appropriate?

• t interval for means

• t test for means

• z interval for proportions

• z test for proportions

Are more than 10% of households now without landline phone service?  2000 American households were surveyed. Which procedure is appropriate?

• t interval for means

• t test for means

• z interval for proportions

• z test for proportions

A __________ gives an interval of plausible values for the _____________. 

• confidence interval, statistic

• point estimate, parameter

• point estimate, statistic

• confidence interval, parameter