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+1 vote

There are several measures of fit in LC, most of which you will find described on page 28 of the LC manual available here: https://www.sawtoothsoftware.com/download/ssiweb/LClass_Manual.pdf.

In a max diff study the null log-likelihood is much larger than in the example given on page 28. How is this calculated, also what is a good measure for percent certainty in a MaxDiff study.

Percent Certainty is probably what you are looking for, as it is scaled from 0 to 100 and acts like a pseudo-rsquared.

Regarding Null log-likelihood, it is computed by taking ln(1/C)*R*T*2

Where:

C = concepts per task

R = number of respondents

T = number of tasks per respondent

(Where T is the number of tasks that each responent saw, which get coded in the estimation file as two tasks per set...a "best" and a "worst" task...hence I'm multiplying by 2.)

Where:

C = concepts per task

R = number of respondents

T = number of tasks per respondent

(Where T is the number of tasks that each responent saw, which get coded in the estimation file as two tasks per set...a "best" and a "worst" task...hence I'm multiplying by 2.)

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