El 22/10/2010 2:11, Martin Sherman escribió: > > Dear List; I just tested a sample distribution using the One Sample > Kolmogorow-Smirnov Test under Non-Parametric Tests---One sample K-S > test and get a K-S Z of .933 with a p value of .349. Indicating that > my sample is consistent with a population that is normally > distributed. I then went and used the Explore procedure and looked at > the results of the K-S test and get some very different results. The > statistic reported is .070 and the p value is .034. I am not sure > what is happening here. Does anyone have any ideas. Thanks, martin > > > *Martin F. Sherman, Ph.D.* > > *Professor of Psychology* > > *Director of Masters Education: Thesis Track > *Loyola College of Arts and Sciences > > ** > Hi Martin:

This difference can be found since SPSS 4.0 (PC+ I think its name was). It is not specific of SPSS 19.

The difference is due to the fact that One sample KS (under Non parametric tests) computes Kolmogorov-Smirnv test WITHOUT the Lilliefors correction, and EXPLORE computes the test WITH Lilliefors correction (to adjust the test to the fact that the sample mean&sd are used, instead of the corresponding parameters mu and sigma). Don't use the first one, since it is over conservative. As a matter of fact, DON'T use the second (KS with Lilliefors correction) either, since Shapiro-Wilk test has been proven to be better (the best, I might add).

Best regards, Marta GG

-- For miscellaneous SPSS related statistical stuff, visit: http://gjyp.nl/marta/