Question

A clinical trial was conducted to test the effectiveness of a drug used for treating insomnia in older subjects. After treatment with the drug, 15 subjects had a mean wake time of 90.7 min and a standard deviation of 44.9 min. Assume that the 15 sample values appear to be from a normally distributed population and construct a 90% confidence interval estimate of the standard deviation of the wake times for a population with the drug treatments. Does the result indicate whether the treatment is effective?

Answer #1

At 90% confidence interval the critical values are = = 23.6848

= = 6.5706

The 90% confidence interval for population standard deviation is

sqrt((n - 1)s^2/) < < sqrt((n - 1)s^2/)

= sqrt(14 * (44.9)^2/23.6848) < < sqrt(14 * (44.9)^2/6.5706)

= 34.52 < < 65.54

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