Wilcoxon Test

Question 1

When is it appropriate to use the Wilcoxon test?

Answer 1

When the sample is small and the distribution is not normal (ie nothing known about the background POPULATION)

Question 2

What test statistics do you use?

(i) M=/ a
(ii) M>a
(iii) M<a></a>

Answer 2

(i) The smaller of W+ and W-
(ii) W-
(iii) W+

Question 3

When do you accept the test statistic?

Answer 3

When it is less than the critical value

Question 4

Assumption?

Answer 4

Symmetrical distribution about the median (if symmetrical about median then median=mean)

Question 5

Why is the test significant if the test statistic is LESS than the critical value?

Answer 5

Because if the test statistic is small then the other must be large and there will be a big difference between W+ and W-, thus indicating that the supposed median is not in fact in the centre of the data