Exam 15: Non-Parametric Tests

Nonparametric tests are still inferential tests.

non-parametric and parametric tests make different assumptions about data

In 2017, Nintendo (a Japanese video game company) released a new console called the Nintendo Switch. Nintendo was interested to see how existing customers with their previous generation console (i.e., the Wii U) rate the new product. Below are data of individuals who rated the first console and now rated the Nintendo Switch. Nintendo decided that given the small sample and ranked data, they would use a Wilcoxon Ranked-Sign test. Wii U Switch 7 8 5 9 6 7 4 2 8 6 9 10 2 9 4 8 7 9 7 8 What is the conclusion?

The Mann-Whitney U test makes assumptions about which of the following?

The Mann-Whitney U-test is the nonparametric equivalent of a dependent samples t-test.

Why is it a problem if data are skewed when considering parametric tests?

Generally speaking, if a nonparametric test is used on rank data, the dataset is on a ___________ scale.

If you have quantitative data that is skewed, which of the following can be used to "unskew" it?

After conducting a Mann-Whitney U test, how do you determine statistical significance?

When conducting a Mann-Whitney U-test, if your calculated U-value is smaller than that of the critical value, than the test is considered statistically significant.

If the data are skewed, one should try use a parametric test instead of resorting to nonparametric tests.

Do men and women differ in the way they rate the cuteness of babies? In a study, a team of researchers examined whether gender differences existed in ratings for infants. The data below show average ratings by male and female participants for infant pictures. The team used a Mann-Whitney U test to compare the two groups. Higher scores indicate that the participant thought the image represented a cuter baby. Men Women 7.5 8.5 6.4 6.6 3.7 7.5 8.9 6.9 4.5 7.3 6.7 4.6 5.3 7.7 5.7 8.8 6.8 9.4 7.0 9.7 Is the difference significant if the test were two-tailed?

The data below that records the number of inches of snowfall in different parts of the country Score 22 24 26 47 52 36 44 26 35 59 21 Are there any ties? If so, at which rank?

The degrees of freedom in a Wilcoxon Signed-Rank is based on the number of matched pairs as opposed to the number of individual data points.

One method of dealing with skewed data is to use its rank order instead of actual values.

Do men and women differ in the way they rate the cuteness of babies? In a study, a team of researchers examined whether gender differences existed in ratings for infants. The data below show average ratings by male and female participants for infant pictures. The team used a Mann-Whitney U test to compare the two groups. Higher scores indicate that the participant thought the image represented a cuter baby. Men Women 7.5 8.5 6.4 6.6 3.7 7.5 8.9 6.9 4.5 7.3 6.7 4.6 5.3 7.7 5.7 8.8 6.8 9.4 7.0 9.7 What is the critical value, if you assume alpha = .05 and a two-tailed test?

A statistical method to measure hidden or latent variables from observed data is…

Do men and women differ in the way they rate the cuteness of babies? In a study, a team of researchers examined whether gender differences existed in ratings for infants. The data below show average ratings by male and female participants for infant pictures. The team used a Mann-Whitney U test to compare the two groups. Higher scores indicate that the participant thought the image represented a cuter baby. Men Women 7.5 8.5 6.4 6.6 3.7 7.5 8.9 6.9 4.5 7.3 6.7 4.6 5.3 7.7 5.7 8.8 6.8 9.4 7.0 9.7 Calculate the Mann-Whitney U-test U-value and determine the smaller of the two values.

All measurement scales can be manipulated with mathematical operations like addition and division

There are three types of skewed data: positive, negative, and one-dimensional