MODEL: A General Program for Estimating Parametrized Model Schedules of Fertility, Mortality, Migration, and Marital and Labor Force Status Transitions

Demography has been characterized as the quantitative study of fundamental demographic processes, such as mortality, fertility, migration, and marriage. These processes may be viewed as transitions that individuals experience during the course of their lifecycle. Individuals are born, age with the passage of time, enroll in school, enter the labor force, get married, reproduce, migrate from one region to another, retire, and ultimately die. These transitions contribute to changes in various population stocks through simple accounting identities. For example, the number of married people at the end of each year is equal to the number at the beginning of the year plus new marriages and arrivals of married migrants less divorces, deaths, widowings, and the outmigration of part of the married population. The study of transition patterns generally begins with the collection of data and the estimation of missing observations, continues with the calculation of the appropriate rates and corresponding probabilities, and often ends with the generation of simple projections of the future conditions that would arise were these probabilities to remain unchanged