Nonmetric Data Analysis

What are the assumptions made as it relates to metric data?

• Continuous data (meaningful intervals)

• Equal variance (also implying meaningful intervals)

• Data are distributed normally

When is ordinal data analysis used?

• Used where the data are ordinal in nature (also called ranked data)

• Used where the normality assumption is not met with continuous data

What is involved in ordinal data analysis?

Involves scales that are mathematic and relational, but intervals are not subject to metric or scientific properties

What are examples of ordinal scales?

• Epworth Sleep Scale

• Mini-Mental State Examination (MMSE)

• Likert scales

Which test(s) is described as ordinal, two samples, and independent?

• Wilcoxon Rank Sum

• Mann Whitney U

Which test(s) is described as ordinal, two samples, and dependent?

Wilcoxon Sign Rank

Which test(s) is described as ordinal, three or more, and independent?

Kruskal-Wallis

Which test(s) is described as ordinal, three or more, and dependent?

Friedman

What notable about ordinal tests?

Rather than comparing means, we are comparing medians as they are the proper measure of central tendency

When are the Wilcoxon and Mann-Whitney tests used?

Used when we have a two-sample test and wish to test the null hypothesis that there are no differences in the medians

If we have dependent (paired) sample, which test we would use?

Wilcoxon Signed Rank Test