Question

Data are provided to you on test completion times (in minutes) for students who participated in a one-hour review class before test number 1 and for these same students who were also administered test number 2 a month later. However, they did not participate in the review class before test number 2. The goal here is to determine whether there is a significant difference in the test completion time between the students when they had the review class compared to when they did not have the review class. Using software (or by hand):

A. Generate summary statistics (central tendency and variability measures) for the two samples and briefly summarize what they say.

B. Conduct a test of significance for the difference between the mean test completion times of students when they had the review class before the test and when they did not. Show and interpret the results.

C. Construct a 95% confidence interval of the difference between the two population mean test completion times and interpret it.

Answer 1

A)

= Mean completion time when a review class is held before the test

= Mean completion time when a review class is not held before the test

=Standard deviation of time when a review class is held

= Standard deviation of time when a review class is not held

= Number of students who attended review class

= Number of students who did not attend review class

= Population mean for sample 1 (attended review class)

= Population mean for sample 1 ( not attended review class)

B)

TEST STATISTIC:

where

The test statistic follows t distribution with degrees of freedom.

C)

95% Confidence interval for =

where is the confidence level. here t table is used for degrees of freedom.