Why Psychologists Should by Default Use Welch's t-test Instead of Student's t-test with Unequal Group Sizes
By Marie Delacre, Daniël Lakens, C. Leys. 2017
871 citations recorded by the source corpus.
When comparing two independent groups, psychology researchers commonly use Student’s t -tests. Assumptions of normality and homogeneity of variance underlie this test. More often than not, when these conditions are not met, Student’s t -test can be severely biased and lead to invalid statistical inferences. Moreover, we argue that the assumption of equal variances will seldom hold in psychological research, and choosing between Student’s t -test and Welch’s t -test based on the outcomes of a test of the equality of variances often fails to provide an appropriate answer. We show that the Welch’s t -test provides a better control of Type 1 error rates when the assumption of homogeneity of variance is not met, and it loses little robustness compared to Student’s t -test when the assumptions are met. We argue that Welch’s t -test should be used as a default strategy.
Subfields: Computer Networks and Communications, Management Science and Operations Research, Statistics and Probability
View Paper: https://www.semanticscholar.org/paper/54c6a3cff54ec889609d05aa46d0229ec11ccdee
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In Computer Networks and Communications
In Management Science and Operations Research
Citations in the corpus
- Self-Compassion When Coping With Venture Obstacles: Loving-Kindness Meditation and Entrepreneurial Fear of Failure (2019, methodology): “Because unequal cell frequencies can bias conventional analyses like the Student’s t-test, we present analyses using the more robust and nonparametric alternative Welch’s t-test (Delacre et al., 2017; Overall et al., 1995).”