Non-parametric methods Flashcards
disadvantages of non-parametric methods
hold less power than parametric
focus on hypothesis testing rather than on estimation
less flexible
examples of non-parametric methods
Mann-Whitney U test
Wilcoxon Signed-Rank Test
Kruskal wallis
friedman
examples of parametric methods
independent samples t test
paired samples t test
one way analysis of varience
analysis of variance for randomised block design
when is Mann-Whitney U test used
to compare two independent samples when outcome is interval scale but assumptions for t-test are not satisfied OR when outcome is ordinal
what hypothesis is tested in Mann-Whitney U test
H0- median in pop1 = median in pop2
when is a Wilcoxon signed-rank test used
to compare 2 paired samples when outcome is interval scale but assumptions for paired samples t-test is not satisfied OR when outcome is ordinal
what hypothesis is tested in Wilcoxon signed-rank test
H0 - median different between pop1 and 2 = 0
when is Wilcoxon signed-rank test used
comparing an interval scale variable between 2 paired groups
what is the correlation coefficient between 2 variables
measure of the degree of linear association between the variables on a scale between -1 and +1. 0 indicates 2 variables are independent
when is spearman’s rank correlation coefficient used
to measure the degree of association between 2 interval scale variables but assumptions for Pearsons correlation coefficient are not met or when at least 1 variable is ordinal
what hypothesis is tested in Spearman’s
H0 spearmans rank correlation coefficent between variables x and y in the population is 0
