A clinical trial was conducted to test the effectiveness of a drug for treating insomnia in older subjects. Before treatment, 15 subjects had a mean wake time of 102.0 min. After treatment, the 15 subjects had a mean wake time of 96.3 min and a standard deviation of 23.5 min. Assume that the 15 sample values appear to be from a normally distributed population and construct a 95% confidence interval estimate of the mean wake time for a population with drug treatments. What does the result suggest about the mean wake time of 102.0 min before the treatment? Does the drug appear to be effective?
Construct the
95%
confidence interval estimate of the mean wake time for a population with the treatment.
Answer)
Sample mean = 96.3
Sample standard deviation = 23.5
As the population standard deviation is unknown, we will use t table to estimate the interval
Degrees of freedom is = n-1, 15-1 = 14
For df 14 and 95% confidence level
Critical value t from t table is = 2.145
Margin of error = t*(s.d/√n) = 2.145*(23.5/√15) = 13.015160534930
Confidence interval is given by
(Mean - MOE, Mean + MOE)
(83.284839465069, 109.31516053493)
Null hypothesis : Ho : u=102
Alternate hypothesis : Ha : u < 102
Since the interval contains the null hypothesised value 102
We fail to reject the null hypothesis
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