Thursday, May 29, 2008

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.


2 comments:

Anonymous said...

I recently received the opposite comment--claiming ANOVA was more appropriate to compare two groups than a t-test. I hope those two never review the same paper.

jess said...

Ah - saving me the trouble of showing it myself. Thanks, academic rejection!