There is conflicting information about whether a new medication affects a person's ability to concentrate as measured by time spent on a task.

You wish to test the following claim (HaHa) at a significance level of=0.001=0.001. For the context of this problem,d=21d=2-1where the first data set represents a pre-test measure of time on task and the second data set represents a post-test measure of time on task.

Ho:d=0Ho:d=0

Ha:d<0Ha:d<0

You believe the population of difference scores is normally distributed, but you do not know the standard deviation. You obtain the following sample of data:

Pre Test Post test

54.3 49.2

46.4 28.2

57.6 17.5

48.6 21.8

39 -9.5

39.4 38.8

46.8 42.1

43.7 44.3

What is the test statistic for this sample? (Report answer accurate to three decimal places.)

test statistic =

What is the p-value for this sample? (Report answer accurate to four decimal places.)

p-value =

The p-value is...

• less than (or equal to)
• greater than

This test statistic leads to a decision to...

• reject the null
• accept the null
• fail to reject the null

As such, the final conclusion is that...

• There is sufficient evidence to warrant rejection of the claim that the mean difference of post-test from pre-test is less than 0.
• There is not sufficient evidence to warrant rejection of the claim that the mean difference of post-test from pre-test is less than 0.
• The sample data support the claim that the mean difference of post-test from pre-test is less than 0.
• There is not sufficient sample evidence to support the claim that the mean difference of post-test from pre-test is less than 0.