Comparing Poisson and Extra Poisson Models

[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

[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 (108.06 KiB) Viewed 6695 times

And you want to test that the 0.839 is different from zero
That is you test bcons2.1

test.png (19.35 KiB) Viewed 6695 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.

[LiamMS90]

Many thanks!

Liam