2 groups + 1 DV = MADNESS

Today's interesting submission comes from SW who recently received a comment from a reviewer that is confused by math.

"Under participants, why did you use an ANOVA to compare differences between two groups? A t-test is more appropriate."

(sigh)...okay, kids, time for a review of mathematical equivalence: When the number of groups = 2, ANOVA and ttest give the same results.

Group
1	10	25	19	23	17	29	21	14	19	19.67	28.50
2	19	12	21	17	22	15	16	18	17	15.89	9.28

So, Dr./Mr./Miss/Mrs./? reviewer, there you have it. When there are 2 groups, the t-test and ANOVA are mathematically equivalent, but i guess a ttest is more appropriate because it..ummm...who knows why. Anywho, keep sending your snippets and keep noting them.

ROC Curve = Too Complex!!

I recently submitted to a nice little manuscript that several colleagues and i put together that looked at the diagnostic validity of oral reading fluency in predicting reading comprehension. I thought that a Receiver Operating Characteristic Curve analysis would be appropriate, but little did i know that a little convex curve would nearly cost publication...

"ROC is not commonly used in education and although the procedure used for generating the ROC information appears to be correct, it is too complex an analysis and is better suited and understood by the medical world"

I guess if I had inserted some unicorns, it would have distracted the evil curve :)