Friday, March 10, 2006

Re: st: fisher-exact test

On 3/10/06, Stefania Ottone <stefania.ottone@sp.unipmn.it> wrote: > Dear all, > is it possible to apply the Fisher-exact test to an rxc contingency table > (where both r and c are greater than 2)? Do you think a Kolmogorov-Smirnov > test could be more suitable in case of a 3x2 table? > thank you.

From the help page for -tabulate twoway- (-help tabulate twoway-)....

<snip>

exact[(#)] displays the significance calculated by Fisher's exact test and may be applied to r x c as well as to 2 x 2 tables. For 2 x 2 tables, both one- and two-sided probabilities are displayed. For r x c tables, one-sided probabilities are displayed. The optional positive integer # is a multiplier on the amount of memory that the command is permitted to consume. The default is 1. This option should not be necessary for reasonable r x c tables. If the command terminates with error 911, try exact(2). <snip>

If you've got a 2 x 3 table then you shouldn't have any problem running the exact test.

Would need to know more about your data and study design to comment helpfully on whether K-S tests are appropriate, but initially I'd say there is no need.

Neil -- "A wide screen just makes a bad film twice as bad." - Samuel Goldwyn

Email - nshephard@gmail.com / neilshep@cyllene.uwa.edu.au Website - http://slack.ser.man.ac.uk/ Blog - http://slack---line.blogspot.com/ Flickr - http://www.flickr.com/photos/slackline/

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