Why Psychologists Should by Default Use Welch's t-test Instead of Student's t-test
Why Psychologists Should by Default Use Welch's t-test Instead of Student's t-test
复制标题
DOI：
10.5334/irsp.82
复制
发表时间：
2017-04-05
影响因子：
2.5
通讯作者：
Leys, Christophe
中科院分区：
文献类型：
--
作者：
Delacre, Marie;Lakens, Daniel;Leys, Christophe
在比较两个独立的群体时，心理学研究人员通常使用学生t检验。正态性和方差齐性的假设是这个检验的基础。通常情况下，当这些条件不满足时，学生的t检验可能会严重偏差，导致无效的统计推断。此外，我们认为方差相等的假设在心理学研究中很少成立，根据方差相等检验的结果在Student t检验和Welch t检验之间进行选择往往不能提供适当的答案。我们表明，当方差齐性假设不满足时，韦尔奇t检验可以更好地控制第一类错误率，并且在满足假设时，与学生t检验相比，它的稳健性很小。我们认为韦尔奇的t检验应该作为一种默认策略。
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.