Dr JCH Stillwell and Dr A Bailey
22nd November 1999 – 15th December 2000
DETR
The brief aim for this project is to provide the Department with a model that will enable the investigation of the quantitative impacts of alternative economic and policy scenarios on gross flows of population between regions (paras 1 and 12). The model is also required to provide advice on urban-rural shift (paras 4 and 12). In addition, a fundamental feature of the model is that it should be capable of further enhancement, notably so as to produce outputs to a finer spatial scale than regional level and to assist in the preparation of the next set of household projections (paras 5 and 8).The model produced by this study is to be regarded as potentially the first step toward creating a more advanced framework of analysis , with this study concentrating on first-round impacts and not needing to internalise feedback (para 6). The Contractor is also to be pragmatic in dealing with data limitations, suggesting ways of data bridging for this study and putting forward recommendations for subsequent refinement (para 9). The model need to be flexible, easy to use and transparent (paras 7 and 16).
The research team has tailored its approach to conform to these requirements. Its central features are the modelling of out-migration flows from each area by reference to a set of determinant variables and the use of a spatial interaction model (SIM) to distribute migrants between destinations. This framework will allow a range of ‘what if?’ scenarios to be examined. Model calibration and sensitivity testing will embrace several dimensions of space, time and population cohort – up to 100 origins – destination areas, seven single-year periods and disaggregation of migrant flows by seven ‘life-stage’ age groups and sex. The calibration will involve determining which are the appropriate variables that affect each set of migration patterns and gathering the necessary data on these variables. Once the optimal form of the model has been identified, a user-friendly software program will allow many different scenarios to be run to examine the effects of various possible policies on migration patterns.