luutu se of the cortex.1 84.5 Twenty institutionalized epileptie patients partic

Question

luutu se of the cortex.1 84.5 Twenty institutionalized epileptie patients partic ipated in a study of a new anticonvulsant drug, valpro- ate. Ten of the patients (chosen at random) were started on daily valproate, and the remaining 10 received an p of 30 postmenopausal women were given identical placebo pill. During an 8-week observation ed estrogen for one month. Plasma levels of period, the numbers of major and minor epileptic sei- activator inhibitor type 1 (PAI-1) went zures were counted for cach patient. After this, all f the women, but went up for 8 women.1 patients were "crossed over" to the other treatment, or a sign test, with a nondirectional alterna- and seizure counts were made during a second &-week observation period. The numbers of minor seizures are ull and alternative hypotheses in context. given in the accompanying table.7 Test for efficacy of valproate using the sign test at = 0.05. Use a direc- ttenal alternative. (Note that this analysis ignores the ible effect of time-that is, first versus second 0, what is your conclusion regarding Ho? ntal exercise build “mental muscle"? In one question, 12 littermate pairs of young male observation period.) Section 8.5 The Wilcoxon Signed-Rank Test 331 Valproate Placebo iod Patient Valproate eriod riod Paticnt number Placcho pe riod 37 52 12 20 .^4x ENG 11/7/2017

Explanation / Answer

here the hypothesis are

null H0: No difference in median of the signed differences.
alternate H1: Median of the signed differences is less than zero.

there are 15 positive sign and 4 negative sign and one is zero.

The sample size in this question was 20, with one zero, so n = 19

Find the p-value using a binomial distribution table or use a binomial calculator. I used the calculator, putting in:

p-value=0.0074 ( using ms-excel =BINOMDIST(4,19,0.5,0))

since p-value is less than alpha=0.05, we fail to accept H0 and conclude that there is effect of valporate.

pacebo valproate difference sign 37 5 32 + 52 22 30 + 63 41 22 + 2 4 -2 - 25 32 -7 - 29 20 9 + 15 10 5 + 52 25 27 + 19 17 2 + 12 11 1 + 7 8 -1 - 9 8 1 + 65 30 35 + 52 22 30 + 6 11 -5 - 12 1 11 + 54 31 23 + 27 15 12 + 36 13 23 + 5 5 0 NA

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