Question

The consumption of caffeine to benefit alertness is a common activity practiced by 90% of adults in North America. Often caffeine is used in order to replace the need for sleep. One recent study! compares students' ability to recall memorized information after either the consumption of caffeine or a brief sleep. A random sample of 35 adults (between the ages of 18-39) were randomly divided into three groups and verbally given a list of 24 words to memorize. During a break, one of the groups takes a nap for an hour and a half, another group is kept awake and then given a caffeine pill an hour prior to testing, and the third group is given a placebo. The response variable of interest is the number of words participants are able to recall following the break. The summary statistics for the three groups are in the table below. We are interested in testing whether there is evidence of a difference in average recall ability between any two of the treatments. Thus we have three possible tests between different pairs of groups: Sleep vs Caffeine, Sleep vs Placebo, and Caffeine vs Placebo. Standard Group Sleep Caffeine Placebo Sample size 12 12 Mean 15.25 12.25 13.70 Deviation 3.3 3.5 3.0 Mednick S., Cai D., Kanady J., and Drummond S., "Comparing the benefits of caffeine, naps and placebo on verbal, motor and perceptual memory", Behavioural Brain Research, 2008; 193: 79-86. (a) In the test comparing the sleep group to the caffeine group, the p-value is 0.003 What is the conclusion of the test? 0. In the sample, which group had better recall ability? According to the test results, do you think sleep is really better than caffeine for recall ability?

Answer 1

(a) Since, the p-value is less than the level of significance if considered 0.05, reject the null hypothesis Ho.

Sleep group had better recall ability.

Yes, I do think that Sleep is really better than caffeine for recall ability because of higher mean.

(b) Since, the p-value is greater than the level of significance 5% or 0.05, we do not reject the null hypothesis Ho.

If the significance is 10%, the p-value is less than the level of significance 10% or 0.10, we reject the null hypothesis Ho.

There evidence of difference of mean recall ability between these two groups is not strong.

(c) Since, the p-value is greater than the level of significance 5% or 0.05, we do not reject the null hypothesis Ho.

Caffeine group had better recall ability.

Yes, Caffeine impairs recall ability because it has low mean as compared with others.

(d) Take a nap