THE LOG-LOGISTIC RATE MODEL - 2 GENERALIZATIONS WITH AN APPLICATION TO DEMOGRAPHIC-DATA

The log-logistic distribution is a widely used model in event history analysis. It is well-known that the log-logistic model is able to mode l social processes with monotonically decreasing, as well as nonmonoto nic, reversed U-type hazard rates. In this article two three-parameter generalizations of the log-logistic model are introduced These genera lizations are very flexible in describing a great variety of processes with reversed U-type hazard rates. In addition, the first generalized model allows for separating upward rate shifts (intensity effects)fro m horizontal rate shifts (timing effects). With the second model it is possible to model immunity, that is, allow for the fact that some per sons might not have an event at all. The usefulness of these models wi ll be illustrated by an application to demographic data from the Unite d States and Germany: The effects of education on marriage rates are a nalyzed. Finally, the relationship between the proposed hazard rate mo dels and certain social diffusion processes is investigated.