The official homelessness figures are derived from central government and based upon data submitted to the government by local councils. The single figure presented on the Youth Homelessness Databank is the number of young people accepted by the government as statutorily (officially) homeless and therefore owed a duty to be housed by the state.
In Wales, a recent change in legislation means that local authorities are required to do more to prevent or relieve homeless before people are required to be housed by the state. What this means in terms of the data is, the central government data for 2015/16 is not comparable to data from previous years. For more details on this legislation change and the impact upon the data, see the Gov.wales note here: Statutory Homelessness – Legislative changes from 27 April 2015
For further guidance on central government data, see the following sites:
The local council data included in the Youth Homelessness Databank explores the number of young people that request help from their local council, what support they get (acceptance as statutorily homeless or prevention and relief support) and their reason for becoming homeless.
This data was collected from across England through Freedom of Information requests issued to all 326 local authorities. The returns form for the Freedom of Information requests issued can be found here.
For Wales, Scotland and Northern Ireland the data at a local authority level was requested directly from the respective governments.