Readers of Q.J.E. will say Josh Angrist.
Readers to Freakonomics will say Steven Levitt.
Followers of the Nobel Prize will say (or try to say!), Trygve Haavelmo.

But it turns out, they should say Philip Wright.  The identification (ha ha) was done by Jim Stock and Francesco Trebbi who report:

The earliest known solution to the identification problem in econometrics – the
problem of identifying and estimating one or more coefficients of a system of
simultaneous equations – appears in Appendix B of a book written by Philip G. Wright,
The Tariff on Animal and Vegetable Oils, published in 1928. Its first 285 pages are a
painfully detailed treatise on animal and vegetable oils – their production, uses, markets,
and tariffs. Then, out of the blue, comes Appendix B: a succinct and insightful
explanation of why data on price and quantity alone are in general inadequate for
estimating either supply or demand; two separate and correct derivations of the
instrumental variables estimators of the supply and demand elasticities; and an empirical
application to butter and flaxseed.

Stock and Trebbi have to do a lot of detective work because Sewall Wright, the great geneticist, was the son of Philip and people thought the son might have written Appendix B.  But Stock and Trebbi do a fun econometric analysis of the text of Appendix B and compare it to Philip and Sewall’s other work (this is called stylometrics).  They find that Philip must have written Appendix B.

(HT: Enrico Spolaore and Francesco Trebbi at NBER last week)

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