Re: [ECOLOG-L] Different results from Statview and SPSS
I believe that in SPSS and SAS (JMP is an offshoot of SAS, so probably has similar mathematical underpinnings), you can choose the types of sum of squares that you want. If you do not specifically state which you want, they may have different defaults. Hence the different results. You can go into the help and find out the default and as long as you know which you want, you can then force them to do the one you want. Cheers, Jim MaryBeth Voltura wrote on 09-Jun-09 21:09: I am reviewing an old dataset that I had originally analyzed in Statview (5.0.1), and re-ran some statistics in SPSS (v.16.0), with very different results. I am running ANOVA on food intake, using body mass as a covariate, with 3 experimental diet groups. The two programs produce different sums of squares and utilize different degrees of freedom for the independent variables, thus producing very different p-values. Has anyone working with these two programs run into anything similar? BTW, if I run the ANOVA with no covariate, the sum of squares and F-statistic and p-values match up between Statview and SPSS. Any ideas? ~~ Mary Beth Voltura, Assistant Professor Department of Biological Sciences SUNY Cortland Cortland NY 13045 607-753-2713 marybeth.volt...@cortland.edu -- James J. Roper Smithsonian Tropical Research Institute Bocas del Toro Marine Research Station MRC 0580-03 Unit 9100, Box 0948 DPO AA 34002-9998 Skype-in (USA):+1 706 5501064 Skype-in (Brazil):+55 41 39415715 E-mail - personal: jjro...@gmail.com E-mail - consulting: arsart...@gmail.com STRI Bocas del Toro http://www.stri.org/english/research/facilities/marine/bocas_del_toro/index.php Programa de Pós-graduação em Ecologia e Conservação http://www.bio.ufpr.br/ecologia/ Educational Pages http://jjroper.googlepages.com/ Ars Artium Consulting http://arsartium.googlepages.com/ 9^o 21.122' N, and 82^o 15.390' W In Google Earth, copy and paste - 9 21.122' N, 82 15.390' W
Re: [ECOLOG-L] Different results from Statview and SPSS
This occurs when you calculate mixed effects models. The statistics programs make different assumptions about the error structure and therefore calculate different F values. This is described in Ayres, M. P., and D. L. Thomas. 1990. Alternative formulations of the mixed-model ANOVA applied to quantitative genetics. Evolution 44:221-226. Hocking, R. R. (1973) A discussion of the two-way mixed model. Amer. Statist. 27:148-152 McLean, R. A., Sanders, W. L., Stroup, W. W. (1991) A unified approach to mixed linear models. Amer. Statist. 45: 54-64 At the time when I needed this I talked the issue over with Dr. Brunner, Professor in statistics at the University of Göttingen. He recommended not using the SAS-formulas because they are based on the assumption of negatively correlated interaction terms which he thinks is not very likely. I deal with the issue by having my stats program (JMP) calculate the sum of squares and then calculate the rest in Excel according to the formulas recommended by a stats book I trust (e.g. Kirk, Winer, or Zar). Martin Am 2009-06-10 um 04:09 schrieb MaryBeth Voltura: I am reviewing an old dataset that I had originally analyzed in Statview (5.0.1), and re-ran some statistics in SPSS (v.16.0), with very different results. I am running ANOVA on food intake, using body mass as a covariate, with 3 experimental diet groups. The two programs produce different sums of squares and utilize different degrees of freedom for the independent variables, thus producing very different p-values. Has anyone working with these two programs run into anything similar? BTW, if I run the ANOVA with no covariate, the sum of squares and F-statistic and p-values match up between Statview and SPSS. Any ideas? ~~ Mary Beth Voltura, Assistant Professor Department of Biological Sciences SUNY Cortland Cortland NY 13045 607-753-2713 marybeth.volt...@cortland.edu
[ECOLOG-L] Different results from Statview and SPSS
I am reviewing an old dataset that I had originally analyzed in Statview (5.0.1), and re-ran some statistics in SPSS (v.16.0), with very different results. I am running ANOVA on food intake, using body mass as a covariate, with 3 experimental diet groups. The two programs produce different sums of squares and utilize different degrees of freedom for the independent variables, thus producing very different p-values. Has anyone working with these two programs run into anything similar? BTW, if I run the ANOVA with no covariate, the sum of squares and F-statistic and p-values match up between Statview and SPSS. Any ideas? ~~ Mary Beth Voltura, Assistant Professor Department of Biological Sciences SUNY Cortland Cortland NY 13045 607-753-2713 marybeth.volt...@cortland.edu
