Population estimates and projection methods are key demographic techniques that provide information on population levels and trends by creative use of limited data. The more sophisticated methods analyze age-specific data on population size and on births, deaths, and migration in modeling current and future change. This analysis may be based on modeling of past trends or by making use of other measured administrative data that vary with population. In recent years, stochastic forecasting methods have attempted to model the uncertainty surrounding the results of population forecasts.