Question

You wish to test the following claim (Ha) at a significance level of α=0.001. d denotes the mean of the difference between pre-test and post-test scores.

Ho:μd=0

Ha:μd>0

You believe the population of difference scores is normally distributed, but you do not know the standard deviation. You obtain pre-test and post-test samples for n=245 subjects. The average difference (post - pre) is ¯d=0.4 with a standard deviation of the differences of sd=12.9 .

a.) The test statistic's value is (0.4-0)/(12.9/sqrt(245)) = 0.485. What is the test statistic for this sample?

• t, df = 12.9

• paired samples t-test, df = 244

• z

• t, df = 0

• independent samples t-test, df = 244

b.) What is the p-value for this sample? Round to 4 decimal places.

p-value =

c.) The p-value is...

• greater than α

• less than (or equal to) α

d.) This test statistic leads to a decision to...

• reject the null

• fail to reject the null

• accept the null

e.) As such, the final conclusion is that...

• There is not sufficient sample evidence to support the claim that the mean difference of post-test from pre-test is greater than 0.

• The sample data support the claim that the mean difference of post-test from pre-test is greater than 0.

• There is sufficient evidence to warrant rejection of the claim that the mean difference of post-test from pre-test is greater than 0.

• There is not sufficient evidence to warrant rejection of the claim that the mean difference of post-test from pre-test is greater than 0.

Answer 1