Hi Annette, This modified Bonferroni method is for planned comparisons, and it is a good one (still). For posthoc comparisons you need to correct for all possible comparisons of that type (e.g. all possible pairwise comparisons). In that case the Tukey or Ryan (REGWQ) is better. Both are available in SPSS; the Ryan is a bit more powerful.
Charlotte >Hi Rob: > >It sounds to me like you want to do post-hoc comparisons. I was taught, in graduate >school, so it was some time ago, to do all the necessary comparisons I want with >t-tests and then use a bonferroni correction for alpha. According to Simes (1986) you >can rank order the p-values from smallest to largest for all the t-tests you >performed and then determine the critical value by taking each value in order as >follows: for the first critical value it is calculated as (1 times .05)/total number >of comparisons made. The second critical value is (2 times .05)/ total number of >comparisons made. Continue in this fashion for each comparison. As soon as you reach >a nonsignificant comparison you stop. All the others after that are nonsignificant >regardless of the math. But there are other bonferroni corrections you may be able to >find and that make more sense to you. > >Annette > >At 03:14 PM 11/18/2002 -0800, you wrote: >>TIPS folk, >> >>I'm having an SPSS hardship on a research project I'm working on. I have >>not found someone who can help me figure this out on my campus. Perhaps a >>TIPster could help? >> >>I am trying to analyze data using a 2X5 ANOVA. I have two independent >>variables and one dependent variable. The IVs are ethnicity (5 groups) >>and citizenship (2 groups--yes/no) and DV score on a measure (continuous >>variable). >> >>I know there is a main effect for ethnicity on score. >>There is no main effect for citizenship on score. >>There is an interaction for ethnicity and citizenship on score. >> >>So, here's the question: >> >>I want to analyze the differences for each ethnic group whether or not >>they are citizens for score. So, for example, I want to know if it >>matters whether or not Latinos are citizens on their score. >> >>I can get the interaction effects, but I can't figure out how to get SPSS >>to reveal the statistics I'm interested in. My SPSS book says to use an >>/L matrix, but I'm having trouble figuring out how to set up the syntax. >>Does anyone know how to attain what I'm looking for? >> >> >>Thanks for any advice! >> >>Rob >> >> >>Rob Weisskirch, MSW, Ph.D. >>Human Development Program >>Liberal Studies Institute, Building 15 >>100 Campus Center >>California State University, Monterey Bay >>Seaside, CA 93955-8001 >>(831) 582-5079 >>[EMAIL PROTECTED] >> >> >>--- >>You are currently subscribed to tips as: [EMAIL PROTECTED] >>To unsubscribe send a blank email to [EMAIL PROTECTED] > > > >--- >You are currently subscribed to tips as: [EMAIL PROTECTED] >To unsubscribe send a blank email to [EMAIL PROTECTED] -- =============================================== Charlotte F. Manly, Ph.D. Psychological & Brain Sciences Assistant Professor 317 Life Sciences Bldg ph: (502) 852-8162 University of Louisville fax: (502) 852-8904 Louisville, KY 40292 [EMAIL PROTECTED] http://www.louisville.edu/a-s/psychology/ http://www.louisville.edu/~cfmanl01 USE 40208 ZIP CODE FOR FEDEX --- You are currently subscribed to tips as: [EMAIL PROTECTED] To unsubscribe send a blank email to [EMAIL PROTECTED]
