A researcher wanted to understand the effect of a new drug on the cerebral blood

Question

A researcher wanted to understand the effect of a new drug on the cerebral blood flow (CBF) in adult women. The researcher is concerned that CBF may drop to unsafe levels. An experiment was design to compare the CBF of individuals who took the new drug during the course of 1 week, and individuals who took a placebo.

Conduct the appropriate nonparametric test by hand to assess whether adults who take the new medicine have a reduction of CBF compared to those who did not. Conduct the test at the = 0.10 significance level.

Treatment Group 2.7 2.9 2.7 3.9 2.7 2.1 2.6 2.2 4.2 5.0 .7 5.3 Control Group 3.5 2.5 3.8 8.1 3.6 2.2 5.0 2.9 2.3 2.9 5.1

Explanation / Answer

Solution:-

Mann-Whitney Test and CI: Control Group, Treatment group

N Median

Control Group 11 3.500

Treatment group 12 2.700

State the hypotheses. The first step is to state the null hypothesis and an alternative hypothesis.

Null hypothesis: Control< Treatment

Alternative hypothesis: Control > Treatment

Note that these hypotheses constitute a one-tailed test. The null hypothesis will be rejected if the mean difference between sample means is too small.

Formulate an analysis plan. For this analysis, the significance level is 0.05.

Point estimate for 1 - 2 is 0.350

95.5 Percent CI for 1 - 2 is (-0.400,1.799)

W = 147.0

Test of 1 = 2 vs 1 > 2 is significant at 0.1861

The test is significant at 0.1855 (adjusted for ties)

From the above test we can conclude that we have significant evidence in the favor of the claim that  new medicine have a reduction of CBF compared to those who did not take new medicine.

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