5 Aclinical trial is planned to compare an experimental medication tolower blood

Question

       5     Aclinical trial is planned to compare an experimental medication tolower blood pressure to a placebo. Before starting thetrial, a pilot study is conducted involving 10 participants . Theobjective of the study is to assess how systolic blood pressurechanges untreated over time.   Systolic bloodpressures are measured at baseline and again 4 weekslater. Compute 95% confidence interval for the mean differencein blood pressure over 4 weeks.

Baseline   120   145  130   160 152 143 126 121  115 135

4weeks   122   142  135   158   155   140  130   120   124   130

6.       The following data werecollected as part of a study of coffee consumption among maleand females undergraduate students. The followingreflects cups per day consumed:

Male 3   4   6  8   2   1   0   2

Female 5 3 1 2 0 4 3 1

Generate a 95% confidence interval for the difference In meannumbers of cups of coffee consumed between men and women.

Explanation / Answer

Hi. First off, we want to figure out the number thatcorresponds to the 95% CI. Most likely your book will have it (lookunder the t table distribution, figure out your degrees of freedomwhich is total number of people minus 1, look for that number witha 95% CI and you'll get 2.262. We realize that this is notstandard normal distribution because the N is too small (10). Also,there is no standard deviation shown. In this case, we use themodified t formula Xbar1-Xbar2 (the difference betweenthe mean of bp before the drug and after) (+/-) t 1- (a/2) (in other words imput 2.262) times sample standarddeviation/N). In order to find S, you have to divide therange of values/4 (example for baseline 160-115/4). But there are 2samples so summate both of the s/number n and square root the totalresult then multiply. Your answer would be (135.6-134.7) (+/-) (2.262)((11.25/10) +(9.5/10)) Again for your next sample, just do the above procedureagain .905 (+/-) (2.365) (2.375/8 + 3.28/7) and youll get theanswer. Range (.32-.212)

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