Wood's Method -- a Method for Fitting Leslie Matrices from Age-Sex Population Data, with some Practical Applications

This dissertation is dedicated to an exploration of "Wood's Method" -- a novel approach to fitting demographic transition matrices to age and sex population count data. Demographic transition matrices, otherwise known as "Leslie matrices," are extensively used to forecast population by age, sex, and other characteristics. Our implementation of Wood's Method simplifies the creation of age and sex population forecasts greatly by reducing the amount of data necessary to create a demographic transition matrix. Furthermore, the method can be used to infer a demographic component of change (one of migration, fertility, or mortality) if the other two components are specified. In Chapter One, we introduce Wood's Method, as well as showing some illustrative examples. In Chapter Two, we evaluate the accuracy of Wood's Method by crossvalidating age and sex specific forecasts for 3,120 US counties. In Chapter Three, we present a simpler, alternative derivation of Wood's Method with an extensive example and show some extensions to the method made possible by this new formulation. In Chapter Four, we use the method to examine migration rates at the US County level and show important results regarding clustering of migration. Each chapters is independent of the others, but should be read in order. To our knowledge, this is the first time Wood's Method has been used for forecasting human populations. We hope to show its viability as a forecasting and analysis method and sketch directions for further research