Post WJ’s scientific contributions

Microsimulation differs from traditional macrosimulation in using a sample rather than the total population, in operating at the level of individual data rather than aggregated data, and in being based on repeated random experiments rather than average numbers. Here are presented the circumstances in which microsimulation san be of greater value than the more conventional methods. It is particularly relevant when the results of the process being studied are complex whereas the forces driving it are simple. A particular problem in microsimulation results from the fact that the projections are subject to random variation. Various sources of random variations are examined but the most important is the one we refer to as specification randomness: the more explanatory variables are included in the model, the greater the degree of random variation affecting the output of the model. After a brief survey of the microsimulation models which exist in demography, a number of the essential characteristics of microsimulation are illustrated using the KINSIM model for projecting the future size and structure of kinship networks.