Generating a Close-to-Reality Synthetic Population of Ghana

Abstract

The purpose of this research is to generate a close-to-reality synthetic human population for use in a geosimulation of urban dynamics. Two commonly accepted approaches to generating synthetic human populations are Iterative Proportional Fitting (IPF) and Resampling with Replacement. While these methods are effective at reproducing one instance of the probability model describing the survey, it is an instance with extremely small variability amongst subgroups and is very unlikely to be the real population. IPF and Resampling with Replacement also rely on pure replication of units from the underlying sample which can increase unrealistic model behavior. In this work we present a sequential logic for estimating variables using multinomial logistic regressions and the conditional probabilities amongst each variable in order to generate combinations which were not represented in the original survey but are likely to occur in the real population. We also present a model based approach to imputing missing observation responses and apply the methodology to the Ghana Living Standard Survey 5 (GLSS5) in order to generate a comprehensive synthetic population for the Republic of Ghana, including such household and person variables as household size, tribal affiliation, educational attainment and annual income, amongst others. The R language and environment for statistical computing was used as well as the packages VIM and simPopulation in developing and executing the code. Contingency coefficients, cumulative distributions, mosaic plots, and box plots are presented for evaluation in order to demonstrate the effectiveness of the new method in its application to Ghana.