ERIC Number: ED365706
Record Type: RIE
Publication Date: 1993-Apr
Reference Count: N/A
Type I Error Rates for Welch's Test and James's Second-Order Test under Nonnormality and Inequality of Variance when There Are Two Groups.
Algina, James; And Others
Type I error rates were estimated for three tests that compare means by using data from two independent samples: the independent samples t test, Welch's approximate degrees of freedom test, and James's second order test. Type I error rates were estimated for skewed distributions, equal and unequal variances, equal and unequal sample sizes, and a range of total sample sizes. Welch's test and James's test have very similar Type I error rates and tend to control the Type I error rate as well or better than the independent samples t test does. The results provide guidance about the total sample sizes required for controlling Type I error rates. Nine tables are included. (Contains 16 references.) (Author)
Publication Type: Reports - Evaluative; Speeches/Meeting Papers
Education Level: N/A
Authoring Institution: N/A
Identifiers: James Test; T Test; Type I Errors; Variance (Statistical); Welch Procedure
Note: Paper presented at the Annual Meeting of the American Educational Research Association (Atlanta, GA, April 12-16, 1993). Small, light type throughout document.