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 Carl-Etienne Juneau posted on Friday, November 06, 2015 - 12:22 pm
I have an outcome that is skewed to the left. To improve its distribution, I have used its square root.

A colleague suggested I use Poisson or zero-inflated poisson models instead.

How would this choice of modelling impact results?
 Bengt O. Muthen posted on Friday, November 06, 2015 - 1:14 pm
You need to have a count outcome for that, so non-negative integer values.
 Carl-Etienne Juneau posted on Saturday, November 07, 2015 - 5:09 pm
Dear Dr. Muthén,

Yes, I am aware of this.

I can recode my outcome so it has only non-negative integer values. And use zero-inflated poisson models.

Or I can use its square root. And use "normal" (linear?) models instead.

For an outcome that's skewed to the left, how would this choice of modelling impact results?

Would the estimates of coefficients be more accurate with Poisson models?

Would this affect model fit in any way?
 Bengt O. Muthen posted on Monday, November 09, 2015 - 10:11 am
You may want to ask these general modeling questions on SEMNET.
 Carl-Etienne Juneau posted on Monday, November 09, 2015 - 11:00 am
Thanks for the tip! Will try SEMNET.
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