It is known that the blood concentration of the hormone cortisol becomes elevate

Question

It is known that the blood concentration of the hormone cortisol becomes elevated in some animals prior to the start of spontaneous onset of birthing labor. It was desired to know if this is also the case in humans. Three groups of women were studied. The first group had elective caesarian sections (Elective). The second group gave birth either vaginally or via emergency caesarian section following artificial inducement of labor (Induced). The third group gave birth either vaginally or via emergency caesarian section following sponta- neous onset of labor (Spontaneous). Cortisol concentrations were measured in these women at the time they gave birth. The data are below:

Elective: 262, 307, 211, 323, 454, 339, 304, 154

Induced: 465, 501, 455, 355, 468, 362

Spontaneous: 343, 772, 207, 1048, 838, 687

It is desired to test: H0 : Elective = Induced = Spontaneous vs. HA: At least one mean differs from one other mean, using = 0.05.

(a) Graph the data as you see fit. Why did you choose the graph(s) that you did and what does it (do they) tell you?

(b) Use R to perform a Kruskal-Wallis test. Give the code you used and the output. State the p-value. Make a conclusion in the context of the problem, i.e., is there evidence that any of the birthing methods show a change in cortisol levels?

(c) If you found significant differences in part (b), perform all pairwise comparisons using the Wilcoxon Rank Sum Test with Bonferroni correction. Make a conclusion in the context of the problem.

Explanation / Answer

a)   Because Box plot is best plot to see variation in data and comparision.

Here we can see that all groups are diffrent.

b) a=c(262, 307, 211, 323, 454, 339, 304, 154)

    b=c(465, 501, 455, 355, 468, 362)

c=c(343, 772, 207, 1048, 838, 687)

P value = 0.013 is significant at 5 % los

i.e. Any of the birthing methods show a change in cortisol levels

From pair wise comparision we can see that Elective and Induced are significant

also Elective and Spontaneous are siginificant

but Induced and Spontaneous are not significant

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