Publication date: 08/13/2020

Compare Groups: Statistics

The Statistics report for Compare Groups contains the following reports:

Summary

Wilcoxon Group Homogeneity Test

Model Comparisons

Parameter Estimates

Summary

The Summary report contains a row for each group and for the combined data. Each row shows the number of units that failed and the numbers that were left, interval, or right censored. Each row also gives the corresponding mean and standard error. For more information about how the mean and standard error are computed, see Statistical Reports for Survival Analysis in the Survival Analysis section.

Wilcoxon Group Homogeneity Test

This report presents results of the Wilcoxon test for equality of the failure functions. The report gives the chi-square approximation, the associated degrees of freedom, and the p-value for the test. A small p-value suggests that the groups differ. For an example, see Wilcoxon Group Homogeneity Test in the Fit Life by X section. The Wilcoxon test and its generalization to censored data are discussed in Kalbfleisch and Prentice (1980).

Parameter Estimates

The Parameter Estimates outline contains reports entitled Parametric Estimate - <Distribution Name> for each distribution that is fit. For each group, the Parametric Estimate - <Distribution Name> report gives the distribution’s parameter estimates and their 95% level confidence intervals. The confidence level is not affected when you select Change Confidence Level from the red triangle menu next to Life Distribution - Compare Groups.

Individual Group

The tabs within the Individual Group report contain Life Distribution reports for each individual group. For more information about these reports, see Life Distribution Report and Life Distribution Report Options.

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