Question

A clinical trial was conducted to test the effectiveness of the drug zopiclone for treating insomnia in older subjects. Before treatment with zopiclone, 16 subjects had a mean wake time of 102.8 min. After treatment with zopiclone, the 16 subjects had a mean wake time of 98.9 min and a standard deviation of 42.3 min (based on data from “Cognitive Behavioral Therapy vs Zopiclone for Treatment of Chronic Primary Insomnia in Older Adults,” by Sivertsen et al., Journal of the American Medical Association, Vol. 295, No. 24). Assume that the 16 sample values appear to be from a normally distributed population, and test the claim that after treatment with zopiclone, subjects have a mean wake time of less than 102.8 min. Does zopiclone appear to be effective?

Answer 1

H0: = 102.8

Ha: < 102.8

Test statistics

t = - / S / sqrt(n)

= 98.9 - 102.8 / 42.3 / sqrt(16)

= -0.37

This is test statistics value.

Critical value at 15 df with 0.05 level is -1.753

Since test statistics falls in non-rejection region, we do not have sufficient evidence to reject H0.

We conclude that we fail to support the claim.

The Zopiclone does not appear to be effective.