2. A study was conducted to investigate a social skills training program for alc
ID: 3074527 • Letter: 2
Question
2. A study was conducted to investigate a social skills training program for alcoholics. Twenty four "alcohol-dependent" male inpatients (one missing) at an alcohol treatment center were randomly assigned to two groups. The control patients were given a traditional treatment program. The treatment group patients were given the traditional treatment pro- gram plus a class in social skills training (SST). The table below provide the alcohol intake for 1 year Control 1042 1617 1180 973 1552 1251 1151 1511 728 1079 951 1319 SST 874 389 612 798 1152 893 541 741 1064 862 213 Table 2: Alcohol intake for 1 year (a) Test for differences between the two groups using a permutation test at 5% significance level (b) Test for differences using the Wilcoxon rank-sum test at 5% signifi- cance level. (c) Compare the results you obtained in part (a) and (b).Explanation / Answer
We shall use R for all computational purposes. I will provide you the code. Please ask if you have any doubts in the comments below.
A. Permutation test:
x = c(1042,1617,1180,973,1552,1251,1151,1511,728,1079,951,1319)
y = c(874,389,612,798,1152,893,541,741,1064,862,213)
data = c(x,y)
Trt = c(rep("A", length(x)), rep("B", length(y)))
DF = data.frame(data, Trt)
summary(aovp(data~., data = DF))
summary(aovp(data~., data = DF))
[1] "Settings: unique SS "
Component 1 :
Df R Sum Sq R Mean Sq Iter Pr(Prob)
Trt 1 1194720 1194720 5000 < 2.2e-16 ***
Residuals 21 1581069 75289
---
Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
B. Wilcoxon Rank-Sum test
x = c(1042,1617,1180,973,1552,1251,1151,1511,728,1079,951,1319)
y = c(874,389,612,798,1152,893,541,741,1064,862,213)
wilcox.test(x, y, paired = FALSE)
wilcox.test(x, y, paired = FALSE)
Wilcoxon rank sum test
data: x and y
W = 117, p-value = 0.0009807
alternative hypothesis: true location shift is not equal to 0
C. We reject null hypothesis in both the test as p-value is < 0.05
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.