On 11/26/2008 9:51 AM, Andrew Choens wrote: > I was asked by my boss to do an analysis on a large data set, and I am > trying to convince him to let me use R rather than SPSS. I think Sweave > could make my life much much easier. To get me a little closer to this > goal, I ran my analysis through R and SPSS and compared the resulting > values. In all but one case, they were the same. Given the matrix > > [,1] [,2] > [1,] 110 358 > [2,] 71 312 > [3,] 29 139 > [4,] 31 77 > [5,] 13 32 > > This is the output from R: >> chisq.test(test29) > > Pearson's Chi-squared test > > data: test29 > X-squared = 9.593, df = 4, p-value = 0.04787 > > But, the same data in SPSS generates a p value of .051. It's a small but > important difference. I played around and rescaled things, and tried > different values for B, but I never could get R to reach .051. > > I'd like to know which program is correct - R or SPSS? I know, this is a > biased place to ask such a question. I also appreciate all input that > will help me use R more effectively. The difference could be the result > of my own ignorance.
The SPSS p-value is for the Likelihood Ratio Chi-squared test, not Pearson's. For Pearson's Chi-squared test in SPSS (16.0.2), I get p=0.04787, so the results do match if you do the same Chi-squared test. > thanks > --andy -- Chuck Cleland, Ph.D. NDRI, Inc. (www.ndri.org) 71 West 23rd Street, 8th floor New York, NY 10010 tel: (212) 845-4495 (Tu, Th) tel: (732) 512-0171 (M, W, F) fax: (917) 438-0894 ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
