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st: ## Interaction syntax

From   Robin Jeffries <>
Subject   st: ## Interaction syntax
Date   Tue, 11 Jan 2011 15:28:25 -0800

I was under the impression that for a categorical variable 'wave' with
3 levels (0, 1, 2)
and another binary indicator variable 'group' (0,1) then the following
statements are the same:

1) xtlogit (other covar)

2) xtlogit wave1 wave2 group wg1 wg2 (other covar)

where wave1, wave2, wg1, wg2 are the manually created indicators and
interactions for wave and wave*group respsectivly

For most outcomes I am using this with, they produce the exact same
results. However there have been some instances where using the second
method results in a model that won't converge, but the first will.

Is there an explanation for this?

Robin Jeffries
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