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st: Number of instruments needed for growth curve model using xtivreg?
From
David Torres <[email protected]>
To
"[email protected]" <[email protected]>
Subject
st: Number of instruments needed for growth curve model using xtivreg?
Date
Fri, 6 Dec 2013 15:30:48 -0500
Hello, Statalisters,
I'm using xtivreg to carry out a growth model that includes a quadratic term. One of my time-varying predictors is endogenous, so I've instrumented for it using one other variable. Someone questioned me, though, whether it was okay to only include one instrument given that I want to know the impact of the endogenous predictor on the intercept, the linear growth term, and the quadratic growth term? Do I need three instruments in this case? We're both concerned because we've never seen an IV estimation in the context of HLM.
Help.
Thanks,
Diego
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