This paper explores tests of the hypotheses that the tail thickness of a distribution is constant over time. Using Hill's conditional maximum likelihood estimator for the tail index of a distribution, tests of tail shape constancy are constructed that allow for an unknown breakpoint. The...

During his period at the LSE from the early 1960s to the mid 1980s, John Denis Sargan rose to international prominence and the LSE emerged as the world's leading centre for econometrics. Within this context, we examine the life of Denis Sargan, describe his major research accomplishments,...