Nonparametric Three or more groups

Kruskal-Wallis Analysis of Variance of Ranks Test More than two groups, ordinal level data on the DV 27

Example A police psychologist wants to determine whether relaxation or guided imagery enhance the rank-orderings of the crime-solving abilities of police officers. He/she compares them to a control group. 6 in the control group, 6 in relaxation, 6 in imagery 28

Example -- continued Number of Samples: 3 Nature of Samples: independent Independent Variable: type of treatment 29

Example -- continued 4. Dependent Variable and its Level of Measurement: rank ordered judgments, ordinal 5. Target Population: police officers 6. Inferential Statistical Technique: Kruskal-Wallis Analysis of Variance of Ranks Test

Example -- continued 7. H0: H1: Decision Rule: Type of training will have no effect on rank-ordered crime-solving ability H1: Type of training will have an effect on rank-ordered crime-solving ability Decision Rule: If the p-value of the obtained test statistic is less than .05, reject the null hypothesis 31

Example -- continued 10. Obtained Test Statistic: Decision: accept the null hypothesis d.f. = number of samples - 1

Results Section The results of the Kruskal-Wallis Analysis of Variance of Ranks Test involving type of training as the independent variable and rank-ordered crime-solving ability as the dependent variable were not statistically significant. 33

Discussion Section It appears that the type of training police officers receive has no effect on rank-ordered crime-solving ability 34

Kruskal-Wallis Test and SPSS for Windows Statistics, Nonparametric Tests, k Independent Samples Move DV to Test Variable list Move IV to Grouping Variable Define Groups Make sure K-W is checked

Interpreting the Printout Mean ranks Chi-Square (obtained test statistic) Significance (p-value)

Sample Printout