ABSTRACT
For me, delving deeply into the traditional age-period-cohort (APC) problem represents a long-time passion. As noted in the Preface, it began with a talk given by Bill Mason at the University of Oregon in 1987 or 1988. But there were also years of inactivity in this area until I began working on these models again with my colleague Jean Stockard. I had given her some data on the epidemic of youth homicide, and she thought she knew a cohort factor that might account for this phenomenon. I said I knew another one and that I knew how to test it. We were off on the most wonderful collaborative research of my career. As always my substantive interest in problems ignited my methodological interest. For me they go hand in hand. Then the work of Yang, Fu, and Land (2004) and Yang, Schulhofer-Wohl, Fu, and Land (2008) inspired an interest in the technical details of APC constrained models-the major traditional technique in the APC literature-but one that I had never used in substantive research. All this has culminated in this book.
