I have a simple statistical question. I have a sample of 307 people. 111 are in the red group and 196 are the blue group. The correlation between variables x and y in the red group is r= .226 (n=111), p <.05 and in the blue group r=.164 (n=196), p<.05. However, when I run the correlation between x and y in the entire sample (red and blue combined, no missing data) I get a negative correlation, r=-.142 (n=307), p < .05. Now what doesn't make sense to me that two groups individually have positive and significant correlations but the two groups combined can have a negative and significant correlation. So you stats tipsters. Is that statistically possible?
I have checked everything I possibly can in terms of errors in the data or the analyses and have found none. Some suggestions about what I ought to look at? Marie Marie Helweg-Larsen, Ph.D. Associate Professor l Department of Psychology Kaufman 168 l Dickinson College Phone 717.245.1562 l Fax 717.245.1971 Office Hours: Mondays and Tuesdays 2:00-3:30 http://users.dickinson.edu/~helwegm/index.html --- You are currently subscribed to tips as: arch...@jab.org. To unsubscribe click here: http://fsulist.frostburg.edu/u?id=13090.68da6e6e5325aa33287ff385b70df5d5&n=T&l=tips&o=16294 or send a blank email to leave-16294-13090.68da6e6e5325aa33287ff385b70df...@fsulist.frostburg.edu
