The eighties were very good years for music as well as econometrics. Intime-series econometrics, the first half of that decade was dominated by research on unit roots whilecointegration was the queen of the second half. Estimation and testing of a cointegrated system werethe key questions to answer. When I started my dissertation at the end of the eighties, under the supervision of CliveGranger and Robert Engle, you could sense that everyone was of the opinion that the testing problemof the cointegration rank had been solved by Johansen (1988). Johansen applied reduced rankregression techniques to the following error correction model (ECM) (Granger’s old notation is used tokeep the spirit of the eighties) and obtained the corresponding asymptotics. Nevertheless, estimation was still under close scrutiny,and new estimators appeared on a regular basis in the literature. It was also the case howeverthat different methods could lead to very different estimates of the cointegrating vector,and this was the reason Clive and Rob wanted me to start working on the problem. In Gonzalo (1994), I obtained the asymptotic distribution of the principal components (method proposed in Stock and Watson, 1988) and canonical correlations (between the vectorXt andXt−1proposed by Bossaerts, 1988) based estimators of cointegrating vectors and compared theirperformance to the most popular alternatives at the time: ordinary least square (Engle and Granger, 1987), nonlinear least square (Stock, 1987), and maximum likelihood (Johansen, 1988). Thelatter was the clear winner once the dispersion of the finite sample distributions was measured by theinterquartile range instead of the simple variance.
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