When I first began to research the history of econometrics in 1979, it was a fairly common assumption amongst economists that econometrics had no past, no history, before the 1950s. I was glad to find this was not so, and my pages were not to remain blank. But, instead of the decorative collection of antique notions which might have been expected, I had the excitement of discovering that pre-1950 econometrics was bristling with interesting people and functional ideas. No wonder, for it was during this early period that the fundamental concepts and notions of the econometric approach were thought out. This book is the history of those ideas.

Since there was little in the way of existing literature on the development of econometrics, I have relied on the help of many people. First, I should like to thank those pioneer econometricians who patiently answered my questions about what they were doing and thinking anything up to 50 years, or even more, ago. Amongst the founding fathers of the subject, I was able to talk to Trygve Haavelmo, Herman Wold, Richard Stone, Jan Tinbergen, Olav Reiersøl, George Kuznets, and the late Tjalling Koopmans, Sewall Wright and Holbrook Working. All helped me in various ways: they corrected some of my misapprehensions and filled in the gaps in my understanding in the way that only those with personal experience of the events and their time could do.