>On Thu, 15 Nov 2001, Jerry Dallal wrote: >> But, if the null hypothesis is that the means are the same, why >> isn't(aren't) the sample variance(s) calculated about a pooled >> estimate of the common mean?
Another thought on this... A simpler question is, for a one-sample test of the hull hypothesis that the mean is zero, why don't we find a p-value based on something like a t statistic, but in which the variance is estimated by the average squared differences of the data points from zero, rather than from their sample mean? I investigated this once, and came to the conclusion that the final result (after finding the distribution of the test statistic, and calculating p-values on that basis) is no different from the usual t test. Perhaps the same is the case for a two-sample test, which would explain why no one talks about the possibility of doing it this way. Radford Neal ---------------------------------------------------------------------------- Radford M. Neal [EMAIL PROTECTED] Dept. of Statistics and Dept. of Computer Science [EMAIL PROTECTED] University of Toronto http://www.cs.utoronto.ca/~radford ---------------------------------------------------------------------------- ================================================================= Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =================================================================
