How to use Forecasts, Estimates and Projections
Too many figures – which set should I use?
On this website we publish a number of population estimates, all providing slightly different estimates of the number of people in Hampshire now and likely in the coming years. It can sometimes be unclear as to what figure to use when and why the figures differ in the first place. The aim of this note is to try to help users choose the correct figure or set of figures for their needs and to guide users through the reasons why there are differences at all.
Every 10 years a census of the population is carried out. This is the only time a full count of the population is taken. However, between censuses there is still a need to understand the size of a population and its characteristics, and for this reason population estimates are produced with the aim of being as close to the real, but unknown figure, as possible. Each set of estimates will use somewhat different assumptions and it is these differences that result in the slightly varying estimates seen.
The figures published on the facts and figures website
The facts and figures website presents three different sets of ‘between census’ estimates of the population across Hampshire. Two of the sets also provide estimates of the population into the future.
These three sets are –
Small Area Population Forecasts (SAPF)
Produced by Hampshire County Council, they make use of local information on children and dwelling completions as well as the locations of planned dwellings. SAPF are available at small geographical areas including districts, wards and parishes, and provide estimates of both the current population along with future population estimates over the short term (the next 7 years).
Long Term Projections
Again produced by Hampshire County Council and provide a ‘what if’ scenario testing picture of the population of Hampshire. They make use of policy data regarding future dwelling numbers to constrain the population to over the longer term and suggest what the population will look like over the period given the most recently available policy.
Mid Year Estimates (MYE)
Produced by the Office for National Statistics (ONS), the figures provide a local authority level estimates of the current population across the country as a whole.
In terms of what population figure should be used when, here are some general suggestions to help users decide –
This set of figures we feel provides users with our most accurate picture of Hampshire’s population now and over the coming few years due to the use of local level data. They are also the key source if the need is for information for an area smaller than district level.
Long Term Projections
These figures should be used for those interested in looking more longer term at what the population of Hampshire might look like given the most recent Hampshire wide house building policy.
These figures provide an alternative to Hampshire’s SAPF figures at the local authority level. They are also the key source to use when looking to compare Hampshire’s population with other parts of the country.
It’s important to remember that no matter which set of figures are used – they will be an estimate of the population and should be treated as such. Some figures on these WebPages are provided to the individual person, which has been done to give users the flexibility to add values up to their own age and area groupings. However, in order to emphasise the fact that these are estimated figures, when publishing elsewhere we would recommend rounding the figures to the nearest 10 or even 50 people.