Fundamentals of Statistics contains material of various lectures and courses of H. Lohninger on statistics, data analysis and chemometrics......click here for more. 
Home Statistical Tests Means WelchTest  
See also: TwoSample tTest  Small Sample Size, TwoSample FTest  
WelchTest
When comparing means of two independent samples one often encounters the situation of unequal variances, thus preventing the standard twosample t test from being applicable. However, in the case the samples are from normally distributed populations, an adapted ttest can be applied. The adaption is based on the adjustment of the test statistic and the adjustment of the number of degrees of freedom. Please note that the Welch test is an approximate solution, since the problem of unequal variances cannot be solved exactly. In order to apply the Welch test you have to carry out the following steps:


Home Statistical Tests Means WelchTest 
Last Update: 20121008