92013-03-08 10:17:36localhostconverted to 1.6 markup82007-09-05 10:12:01PeterWatson72007-09-05 10:11:38PeterWatson62007-09-05 09:25:12PeterWatson52007-09-05 09:23:59PeterWatson42007-09-05 09:23:40PeterWatson32007-09-05 09:15:19PeterWatson22007-09-05 09:15:03PeterWatson12007-09-05 09:07:06PeterWatsonRules of thumb for eta-squared involving only between subjects factors in the term of intertest are 0.010, 0.059 and 0.13 for small, medium and large effects respectively. If a within subjects factor is involved you also need to specify an estimate of the average correlation (>0) between within subject factor levels. For any non-zero correlations between the levels of the within subject factors eta-squared will be greater reflecting the smaller variation between observations clustered on individuals and yielding greater power. You can construct eta-squared using this spreadsheet.