Reminiscences by Charles Stein

"When I came to Berkeley in 1947 after finishing the work for my Ph.D. at Columbia University I shared an office with Evelyn Fix, Joe Hodges, and Erich Lehmann. All of us discussed our work but somehow Erich and I started to work together in a fairly systematic way on special cases of the theory of testing hypotheses as it had been developed by Neyman and Pearson, Wald, and others. This collaboration led to our first paper on testing hypotheses and one on non-parametric tests. Erich continued to work hard in these directions, leading to influential books on the subjects. We also worked on a rather technical point concerning completeness in the sequential case and, somewhat later, we wrote a paper on optimum properties of tests invariant under the one-dimensional translation group, part of a field I had been interested in for a long time. At the end of the first year, Erich, Joe, Abraham Wald and I went on a walking trip in Yosemite, preceded by some practice hikes in the Bay Area on which we were joined by R.C. Bose. Except for some short trips with nearly the whole department, this was my introduction to the mountains.

After I left Berkeley in 1949, I found it difficult to get back into the habit of working alone, but eventually had some success in working on the problem of estimating the mean of a multivariate normal distribution, and in other, mostly negative results on optimum properties of invariant tests. Later I drifted more into probability theory. The field of statistics has changed a great deal in these fifty years, and I think that Erich has adjusted better to these changes than I have."

[Back to Erich Lehmann's 80th Birthday Celebration]

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