Chi-square test for nested models

servanm

New member
Joined
Mar 27, 2016
Messages
7
Consider2 models A and B. Model A (5 free parameters) is nested within B (6 freeparameters). Imagine that we do an experiment and acquire data from N = 21participants. We fit models A and B to each individual dataset by minimizingPearson's chi-square statistic. Chi-square values are generally lower for modelB than model A, indicating a better goodness-of-fit for model B. I would liketo test whether the improvement in goodness-of-fit for Model B is significantby doing a chi-square test for nested models. I am not sure about how toperform this test. I think I have to compute the difference chi-sq (modelA) -chi-sq (modelB). Remember that the sample size N = 21, so I get 21 chi-squaredifference values. These values should be generally positive, because thegoodness-of-fit is generally worse for model A. The difference should follow achi-square distribution with a number of degrees of freedom df(diff) = df(modelB) - df(model A) = 1. Am I correct? What can I donext ?

 
Consider2 models A and B. Model A (5 free parameters) is nested within B (6 freeparameters). Imagine that we do an experiment and acquire data from N = 21participants. We fit models A and B to each individual dataset by minimizingPearson's chi-square statistic. Chi-square values are generally lower for modelB than model A, indicating a better goodness-of-fit for model B. I would liketo test whether the improvement in goodness-of-fit for Model B is significantby doing a chi-square test for nested models. I am not sure about how toperform this test. I think I have to compute the difference chi-sq (modelA) -chi-sq (modelB). Remember that the sample size N = 21, so I get 21 chi-squaredifference values. These values should be generally positive, because thegoodness-of-fit is generally worse for model A. The difference should follow achi-square distribution with a number of degrees of freedom df(diff) = df(modelB) - df(model A) = 1. Am I correct? What can I donext ?
What are your thoughts?

Please share your work with us ...even if you know it is wrong

If you are stuck at the beginning tell us and we'll start with the definitions.

You need to read the rules of this forum. Please read the post titled "Read before Posting" at the following URL:

http://www.freemathhelp.com/forum/announcement.php?f=33
 
Top