Tag Archives: Questions

Can I get an indulgence for bad control?

We get a lot of questions about bad control.  Here’s an interesting one from Colin Vance: I'd like to estimate the effect of fuel price (which I assume is exogenous) on distance driven. As a control, I would like to include the fuel efficiency of the driver's car. Although efficiency is likely to be endogenous, […]
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P-score in the reg?

Geo. from GA asks this interesting question 'bout the propensity score: I was wondering whether replacing high dimensional covariates (X) in the regression model with their propensity scores (p(X)) was a good idea? That is, Y = a + bT + cX + e becomes Y= a + bT + c(p(X)) + e. The book […]
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Multiple endogenous variables – now what?!

Diligent reader Daniela Falzon, who works at  the World Bank (in France . . . or Washington, DC) writes us with the following interesting problem concerning multiple endogenous variables in 2SLS: I am estimating Y = b0+ b1*X1 +b2* X2 + b3*X1*X2 + X3 Y is a dummy variable X1 is a dummy variable and […]
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Adding lagged dependent variables to differenced models

Reader Christopher Ordowich asks: In sections 5.3-5.4, there is a great discussion of using fixed effects vs. a lagged dependent variable with panel data. I am having trouble reconciling some of this discussion with a section in a recent paper by Imbens and Wooldridge (2008) titled “Recent Developments in the Econometrics of Program Evaluation.” On […]
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Is 2SLS really OK?

Elias Dinas from EUI asks: In section 4.6.1 you explain very clearly the problems from the straightforward use of the 2SLS logic in binary choice and/orendogenous treatment models. You also provide a simple ‘linearized’ alternative but this is useful at the cost of introducing back-door identifying information. It so happens that I have a continuous […]
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