Given that many users will wish to analyse census data over time for comparative geographical units, the I-CeM team endeavoured to identify the parishes of enumeration consistently across all censuses, thus creating the CONPARID variable in the I-CeM dataset - see the I-CeM Guide for a definition. This is based on the work of Professor Sir E. A. Wrigley for England and Wales1, and by Professor Michael Anderson for Scotland.
In creating consistent geographies the basic logic is to amalgamate parishes where necessary so that the geographical territory under consideration remains constant over time. So, for example, assume that part of parish A was transferred to parish B between census years. In order to create a consistent geographical unit overtime one would need to treat them not as separate parishes, but as a single entity. The reasoning for producing a consistent geography variable is that it facilitates comparisons over time, where, as far as possible, like is being compared to like.
Due to the multiple changes in census enumeration geography over time, and the fact that parish boundaries themselves change, the project produced two sets of consistent geography: one for the period 1851-1891, the other for 1901-1911. Mapping of the I-CeM data for England and Wales can be achieved by using these consistent parish variables in combination with the GIS of historical parishes created by Satchell, A.E.M and Kitson, P.K and Newton, G.H and Shaw-Taylor, L. and Wrigley, E.A (2018). 1851 England and Wales census parishes, townships and places. [Data Collection]. Colchester, Essex: UK Data Archive. 10.5255/UKDA-SN-852232, available from the UKDS.
A link between the ID variable in the dbf_file for this GIS can be linked to the I-CeM variable CONPARID via the look-up table below: