Tag Archives: Corrections

How many df in that?!

Reading pp 298-299 with somewhat more care than they were written, Tobias Wuergler from Zurich writes: In order to demonstrate that robust standard errors are likely to be more biased than non-robust under homoskedasticity, you use a bivariate example, where the single regressor is assumed to be in deviations-from-means form. Wouldn't one need, strictly speaking, […]
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42 clusters references swap

The references to Hansen (2007a) and Hansen (2007b) on page 322-323 are swapped.  On page 322, it should be Hansen (2007b) referenced as discussing bias-correction of serial correlation parameters and on page 323, it should be Hansen (2007a) referenced as showing pretty good results for state clustering with modest numbers of states. Steve must have […]
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Typo on p. 136

Careful reader Christian Perez notes that on page 136 the parameter to be estimated in equation 4.1.15 is \rho and not \e as stated in the text.  Thanks Chris!
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Multivariate first stage F . . . NOT

This just in from the ivreg2 team (Chris Baum, Mark Schaffer, and Steve Stillman): How should you construct a first stage F stat to measure instrument strength when you have more than one endogenous variable?  Not by following the instructions we gave at the bottom of page 218.  Althought the theoretical expressions that motivate the […]
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Bbbbb . . . bivariate probit!

Raphael Studer from Switzerland noticed that the bivariate probit likelihood on page 199 looks suspiciously like the likelihood for old fashioned monaural probit. Thanks Raphael – this is indeed the wrong likelihood, so don’t try to maximize that at home, folks.  It works only if you don’t have an endogenous regressor in the first place.  […]
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Typo on page 130

Well, we like the occasional casual relationship as much as the next guy, but on page 130 the relationship between draft-eligibility and earnings is meant to be causal . . . Thanks to Peter Dizikes for pointing this out!
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Typo on page 174

Hendrik Juerges from the University of Mannheim caught this one: Bottom of page 174 — should read: “where rho_1 is LATE using …” — not: “where psi_1 is LATE using …” many thanks Hendrik!
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Just-identified IV

Gary Solon of Michigan State University pointed out to us that our claim on p. 209 that “just identified 2SLS is median unbiased” is not quite correct and that the claim should be qualified. Gary notes that if the first stage is really zero, the just identified IV estimator is centered at the same point […]
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Typos and mistakes on pages 177 and 183

Careful reader Ian Gow from Stanford caught the following two typos/mistakes: Assumption CA1 on p. 177 should read just like assumption A1 on p. 155, except conditional on X_i (the subscript 0 on Y_0i is incorrect). On p. 183, the para beginning “The size of the group of compliers i given by . . .” […]
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Mistake on page 74

Careful reader Israel Arroyo caught this mistake: Sir, I’m reading the amazing “Mostly Harmless” and I’ve found what I believe to be a typo-though maybe is not and I’m just getting dumber- In Chapter 3, p.74, about the end of 2nd paragraph, it says “[…] regression of Yi on Di and Xi is the same […]
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