On 12 Oct 2003 21:09:08 -0700, [EMAIL PROTECTED] (Bin) wrote: > I found the following formula > ************ > Let E be the experimental condition and let C be the control > condition. Let m be the means, s the standard deviations, and n be the > sample size. Then > t = (mE - mC) / SQRT[(s2E + s2C) / n ] > for the case of equal sample sizes, n, in both groups. See Levin > (1999: 25) for the formula when sample sizes differ. > ************ > in my case, the sample sizes is different, But I can not find the > formula. Could you please tell me the formula for t-Test of Difference > of Means with different sapmle sizes?
If Levin was not convenient - You could try the online documentation for the SPSS algorithms. I think this will lead you to two of the usual formulas for t-tests with unequal N. http://www.spss.com/tech/stat/Algorithms.htm There are a couple of ways to use the Welch correction, for cases when the variances are regarded as inherently (not artifactually) unequal. This gives one. -- Rich Ulrich, [EMAIL PROTECTED] http://www.pitt.edu/~wpilib/index.html "Taxes are the price we pay for civilization." . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
