topic Re: Multiple comparisons problem with Cohen's Kappa in Statistical Procedures

Multiple comparisons problem with Cohen's Kappa

anonymous_user — Tue, 28 Apr 2015 21:04:12 GMT

Hey guys;

I am trying to use the Cohen's Kappa statistic to compare the levels of agreement between four raters for four categories. However, the statistic I'm getting from the mAGREE macro is the level of agreement of all raters for each rating

Example output:

Rating Kappa Prob>Z

1 0.58 >.001

2 0.62 >.001

3 0.45 >.001

4 0.78 >.001

The table that I want to end up filling out looks something like this

	Rater 1	Rater 2	Rater 3	Rater 4	Rater 5
Rater 1
Rater 2
Rater 3
Rater 4
Rater 5

What I am thinking of doing is calculating Kappa statistics for all combinations of raters. But then my question is, does that count as multiple comparisons and would it increase my levels of Type I error? Thanks.

Re: Multiple comparisons problem with Cohen's Kappa

plf515 — Wed, 29 Apr 2015 02:43:41 GMT

Computing a p value for Cohen's kappa seems rather odd in the first place. You would never expect the null hypothesis to be true. If it were even close to true, then there wouldn't even be a point to computing an agreement statistic and even a highly significant kappa may be quite low for any practical purpose.

So, doing many kappas does increase the chance of type I error, but if there is even a tiny chance of a type I error, something is very wrong.

Re: Multiple comparisons problem with Cohen's Kappa

Ksharp — Wed, 29 Apr 2015 12:17:21 GMT

"does that count as multiple comparisons and would it increase my levels of Type I error?"

Sorry.If I was right. You messed it with ANOVA . Agree test is not ANOVA , therefore there should not be multiple comparisons ,Type I error .