Edinburgh Napier University

  The use of sigmoid trend models, particularly the logistic model, was once popular among demographers. However, by 1940 the approach had fallen out of favour, being criticized for giving poor results and having no theoretical validity, and it was considered that models of total population were of little practical interest, the main forecasting procedure adopted being the `bottom-up cohort component' method. In the light of poor forecasting performance from component methods, this paper reassesses the use of simple trend models. It is demonstrated that useful models can be obtained from which a model of the birth rate can be derived. When these models are recast in a recursive parameterization, it is shown that satisfactory forecasts can be obtained.