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Help desk => Questions and Answers => Topic started by: sanei on May 08, 2012, 06:43:57 AM

Title: confidence interval
Post by: sanei on May 08, 2012, 06:43:57 AM
Dear professor

For the MNSQ fit statistics you provide a ninety-five percent confidence interval for the expected value of the MNSQ in ConQuest. Is it possible I provide confidence intervals with other percent?

I need a confidence interval that equal to (0.7 , 1.3).

I wonder if I can ask you to help me.

Best regards

E.sanei


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Title: Re: confidence interval
Post by: ConQuest on May 08, 2012, 06:59:20 AM
Sanei,

for the MNSQ confidence intervals normality is assumed because the degrees for freedom is (typically very)large.  Under the null hypothesis of model fit the MNSQ has an expecation of 1 and a variance that is computed internally, but not actually printed by ConQuest 3.0.   To obtain this number you could subtract the lower 95% CI value from one and divide by 1.96 to get the SE.  The to get an alternative find the appropriate nornmal deviate (eg 1.645 for a 90% interval) multiply that by the CI obtained above and substract from 1.0 for lower bound and add to 1.0 for the upper bound.

OK?

Ray
Title: Re: confidence interval
Post by: sanei on May 08, 2012, 07:12:52 AM
you are wright.
thank you so much for your help.