Question 1
A sample of nurses with affiliation to private hospitals (affiliation = 0) and to university hospitals (affiliation = 1) was asked to rate their confidence in making the right decisions based on their level of ongoing inservice professional development. Use a Mann-Whitney U-test to determine if the distribution of confidence in each group is the same. The file is the first tab in “nonparametric.xlsx.”
Be sure to always write the null and alternate hypotheses, so that the decision is made in the correct direction. Also, conduct all as two-tailed tests at α = 0.05.
Question 2
In the previous item, we used the Mann-Whitney test rather than an independent t-test. Why might we Mann-Whitney rather than the t-test?
Question 3
In the third tab of the same file (nonparametric_sheets.xslx), there are data for the selling prices of homes in a ZIP code and the square footage of those homes. Use the Spearman rank correlation to determine if there is a significant correlation between the home price and the square footage.
A table of Spearman rank significance values is located in the file.
Question 4
Why did we not just use the Pearson correlation for the previous item? That is, what is the Pearson correlation influenced by that the Spearman is not?
Question 5
A restaurant wondered if there was a difference in the number of refills of soda ordered by those aged 18-24 (age = 0) and those aged 13-17 (age = 1). Use the Mann-Whitney U-test to determine if the distribution of soda refills is significantly different for the two groups.
Question 6
An organization was attempting to determine whether there was congruence between the rating of their hiring personnel in rating new employees during their interview presentations. The file “Spearman 2” to determine the Spearman rank correlation between the judges’ ratings.