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Comparing Poisson and Extra Poisson Models

Posted: Sat Jul 28, 2018 2:30 pm
by LiamMS90
Dear Colleagues,

I am trying to compare a two-level Poisson model and a two level Extra Poisson model. From what I have read, in Mlwin this can only be done with a Wald test.

I was just wondering how to set up the Wald test or if anyone could point me in the direction of some instructional literature that might help? I have not been able to find any.

Many thanks,

Liam

Re: Comparing Poisson and Extra Poisson Models

Posted: Mon Jul 30, 2018 10:41 am
by ChrisCharlton
I asked Kelvyn Jones about this and he gave the following response:
If you want to do a Wald test in MLwiN – use the intervals and test window to test whether the additional term is different from zero.

Here is a simple NBD model - the extra term is associated with pi-squared
model.png
model.png (108.06 KiB) Viewed 872 times
And you want to test that the 0.839 is different from zero
That is you test bcons2.1
test.png
test.png (19.35 KiB) Viewed 872 times
And you see that p is very small so there is a difference – the test is quite approximate however and people often divide by 2 to get a one-tailed test.

Re: Comparing Poisson and Extra Poisson Models

Posted: Tue Aug 07, 2018 11:37 am
by LiamMS90
Many thanks!

Liam