Found this of interest amongst yet another PLI saying a local plan had understestimated housing need.
although Dr Woodhead uses DCLG projections and other official ONS/Census material and refers to recognised housing and employment forecasting models, his own methodology is not as transparent as it could be and the range of assumptions used are strongly disputed by other parties. He considers several population/household figures and projections, headship rates, economic and social factors, with a wide range of assumptions. However, he does not use established models such as “POPGROUP” or “HEaDROOM”, which he feels might over-estimate housing and employment needs; but such models provide a consistent approach, provided the assumptions are realistic and the implications are acknowledged. His figures are based on 2008/2010 household/population data, but his recommendation is also supported by the latest 2011-based interim household projections, which have acknowledged shortcomings, including caution about using them for projections beyond 2021. His methodology and approach also use rather pessimistic forecasts, with confusing references to differing sets of data, timescales and assumptions.
Good that the inspector refers to a new rarely standard forecting approach HEaDROOM, Bit it just a spreadhseet with assumptions, and surely these can be challenged. As the inspector says ‘such models provide a consistent approach, provided the assumptions are realistic and the implications are acknowledged. ‘ The problem with Dr woodheads work would not appear to be the mechanics of his demographic model but the unrealistic pessimism of his assumptions.