The Housing White paper
[local planning authorities will now be] “expected to provide neighbourhood planning groups with a housing requirement figure, where this is needed to allow progress with neighbourhood planning. As part of the consultation on a new standard methodology for assessing housing requirements, we will seek views on whether a standard methodology could be developed for calculating housing need in a neighbourhood plan area“.
Firstly local people priced out of the area wont show up, neither will in migrants for work or retirement, on any measure of housing need arising from the area. Whether the method is based on local surveys, census data etc. This produces a systematic under representation of ‘local’ need in locally based methods. This has been a systematic problem. The old Cotswolds Local Plan for example said their was no housing need in the prettiest Cotswold Villages because no one living in them said they were in need in local surveys. This is like asking residents of Mayfair if they are ion need of food banks.
Secondly most neighbourhood plan areas are too small to get meaningful data. Census OAs rarely match to parishes. Therefore you need to make statistical estimates for a parish which might include data from several OAs and some OAs may include data from other parishes. This requires advanced GIS statistical techniques such as aerial interpolation and empirical Bayesian Kriging to estimate, and probably using an intermediate interpolation matching population to household/postcode locations using NOMIS data to account for the correct clustering of population in villages as opposed to across the whole countryside. By default interpolation techniques assume the population by default is evenly spread which clearly it is not. Also the smaller the area the larger the standard error, which is why quite rightly SHMAS usually cluster villages to reduce the error to acceptable parameters.
Thirdly a crude carving up of need per village is the opposite of planning. Villages vary hugely in terms of their constraints and opportunities (both land availability and sustainability of services and location). A carving up would see too much housing in the least sustainable and most constrained villages.