Philip Green Wright (October 3, 1861 – September 4, 1934) was an American economist who in 1928 first proposed the use of instrumental variables estimation as the earliest known solution to the identification problem in econometrics.
Philip Wright grew up in Medford, Massachusetts, and in 1884 graduated from Tufts College with a bachelor of mechanic arts (AMB) degree.
From 1884 to 1886 he taught mathematics at Buchtel College in Akron, Ohio, after which he attended Harvard University and graduated with a master of arts (AM) degree in economics in 1887.
In addition to teaching mathematics (through calculus), astronomy, and economics, he also taught classes in fiscal history, surveying, English composition, and literature and was director of the gymnasium.
Wright taught a class called "Daily Themes" in which students were required to write one or two-page essays each day and then critique their work.
Sandburg was influenced not only by Wright's interests in poetry and literature, but also by his political theory and emphasis on social consciousness.
Wright wrote the foreword, writing that the contents have "the delightful bloom and freshness and spontaneous enthusiasm of expression of one who is witnessing the sunrise for the first time.
In 1913 he obtained employment at Harvard University, first as the assistant to Frank W. Taussig, his former advisor, then as an instructor in economics.
But in Moore's book, his statistical demand curve for one product, pig iron, infamously yielded a positive relationship between price and quantity.
At about the same time, the identification problem was also independently discovered by Marcel Lenoir in his 1913 doctoral dissertation, Etudes sur la Formation et le Mouvement des Prix, and by R.A. Lehfeldt in his 1915 review of Moore's book for the Economic Journal.
He worked at Brookings until his retirement in 1929, writing several monographs and scholarly articles on international trade and tariffs.
[8]: 456, 445–446 [19] In an appendix of his 1928 book, The Tariff on Animal and Vegetable Oils, Wright proposed instrumental variables regression as a solution to the identification problem for a supply-and-demand model.
[20] Wright needed to estimate the slope of a demand curve in order to measure the impact of a tariff.
In 2003 James H. Stock and Francesco Trebbi endeavored to determine authorship by conducting stylometric analysis, comparing word usage and grammatical constructions to other samples of each author's writings, and concluded that the evidence clearly supports Philip as the writer.
[7] Later, Stock and Kerry Clark obtained correspondence between Philip and Sewall Wright written during the winter of 1925–26 in which they worked out the two solutions to the identification problem, instrumental variables and path analysis.
The letters also showed that prior to publication of the appendix, Philip Wright had submitted a paper describing the research to the Quarterly Journal of Economics, but it was rejected.