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Re: st: Chi-square test with probabilities

From   Ronan Conroy <>
To   "" <>
Subject   Re: st: Chi-square test with probabilities
Date   Tue, 11 Nov 2008 18:46:31 +0000

On 11 Nov 2008, at 17:19, Christoph Merkle wrote:

Actually I'm only interested if the mean of these peobabilities over
participants is different from hyposized proportions. If I use a
simple ttest I can only test each of the variables one by one. But I
want to test the distribution over the ten

If the events are mutually exclusive and collectively exhaustive, then the probabilities ought to add up to 1, but I fear that they won't.

I think you are better testing one-by-one, using a t-test to test the hypothesis that the mean guessed probability is the same as the actual value, unless you have a hypothesis that is independent of the probability being guessed (such as 'humans overestimate the chances of rare events happening') in which case, I would treat it as a repeated measures design.

Ronan Conroy
Royal College of Surgeons in Ireland
Epidemiology Department,
Beaux Lane House, Dublin 2, Ireland
+353 (0)1 402 2431
+353 (0)87 799 97 95
+353 (0)1 402 2764 (Fax - remember them?)

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