it's called the behrens-fisher problem ... there is nothing that says that population variances HAVE to be equal
essentially what you do is to be a bit more conservative in your degrees of freedom ... most software packages do this as the default ... or at least give you the choice between making an assumption of equal population variances ... or not At 11:48 PM 2/14/02 +0100, Matthias wrote: >Hello, > >would be nice if someone can give me some advice with regard to the >following problem: > >I would like to compare the means of two independent numerical sets of data >whether they are significantly different from each other or not. One of the >two underlying assumption to calculate the T-Test is not given (Variances >are assumed to be NOT equally distributed; but data is normally >distributed). What kind of (non?)parametric-test does exist - instead of the >T-Test - to calculate possible differences in the two means? >I'm using SPSS for further calculations. > >Thank you for your time and help, > >Matthias > > > > > >================================================================= >Instructions for joining and leaving this list, remarks about the >problem of INAPPROPRIATE MESSAGES, and archives are available at > http://jse.stat.ncsu.edu/ >================================================================= ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at http://jse.stat.ncsu.edu/ =================================================================
