Applying model migration schedules to represent age-specific migration flows James Raymer University of Southampton Andrei Rogers University of Colorado Paper prepared for presentation at The Third International Population Geographies Conference, Liverpool, 19-21 June 2006
Outline Research question and significance The multiexponential model migration schedule Age-specific patterns of migration in the U.S. West Application of model migration schedules to represent age-specific migration flows Some results Summary and discussion
Research question and significance How can known regularities of age-specific migration be better used to estimate migration flows? Significance Age-specific data are needed for planning and understanding patterns Often these data are incomplete or not available
The Rogers-Castro (standard) multi-exponential model migration schedule Model schedules are used to: Identify regularities Smooth irregular data Infer missing data Represent unknown age profiles Rogers A and LJ Castro. 1981a. Model migration schedules. RR-81-30, International Institute for Applied Systems Analysis, Laxenburg, Austria.
The four main families of multiexponential model migration schedules
Age profiles of U.S. interstate migration and immigration, 1985-1990 Aim: develop a method for obtaining estimates of age-specific migration flows given various levels of incompleteness in the data Key assumption: aggregate migration levels are known
196 age profiles Model migration schedule of observed age profiles of migration in the U.S. West, 1985-1990
The four age profiles of interstate migration in the U. S The four age profiles of interstate migration in the U.S. West, 1985-1990
118 age profiles 34 age profiles 35 age profiles 9 age profiles Model migration schedules of observed standard, young standard, old standard, and elderly retirement age profiles of migration in the U.S. West, 1985-1990
Model migration schedules (standardized to unit area) of observed age profiles of migration in the U.S. West, 1985-1990
Comparison of different age-specific models used to predict age profiles of interstate migration in the U.S. West, 1985-1990
Comparison of different age-specific models used to predict age profiles of migration from California to Arizona, Colorado, Montana, and Utah, 1985-1990
The observed and predicted migration flows from California to Arizona, 1985-1990
The observed and predicted migration flows from California to Colorado, 1985-1990
The observed and predicted migration flows from California to Montana, 1985-1990
The observed and predicted migration flows from California to Utah, 1985-1990
Summary and discussion Four age profiles of migration were used to represent 196 flows Can extensions can be made to other contexts? Intercensal survey data International migration between countries in the EU Less developed nations Future work involves identifying key factors that explain different age profile shapes