|Source||Department for Communities and Local Government (DCLG) - U.K.|
|Release||Vacancy Compared With Tenure|
|House Price Index||Dec 2020||461.97||458.2||1993Q1=100, SA||Monthly|
|House Price Index for Existing Homes||2020 Q4||464.97||450.93||1993Q1=100, NSA||Quarterly|
|House Price Index for New Homes||2020 Q4||488.16||481.12||1993Q1=100, NSA||Quarterly|
|House Price Value||Dec 2020||230,920||229,721||GBP, NSA||Monthly|
|House Price Value for Existing Homes||2020 Q4||271,399||263,207||GBP, NSA||Quarterly|
|House Price Value for New Homes||2020 Q4||192,377||189,602||GBP, NSA||Quarterly|
|Building Completions||2019 Q2||55,590||48,940||#, NSA||Quarterly|
|Housing Starts||2019 Q2||49,210||48,690||#, NSA||Quarterly|
|Residential Building Completions||2019 Q2||55,590||48,940||#, NSA||Quarterly|
|Dwelling Stocks||31 Mar 2014||28,073||27,914||Ths. #||365 days|
The ONS House Price Index (HPI) publishes figures for mix-adjusted average house prices and house price indices for the UK and its component countries and regions. The index is calculated using mortgage financed transactions that are collected via the Regulated Mortgage Survey by the Council of Mortgage Lenders. These cover the majority of mortgage lenders in the UK.
The HPI Statistical Bulletin provides comprehensive information on the change in house prices on an annual basis. It also includes analysis by country, region, type of buyer (first time buyers and former owner occupiers) and type of dwelling (new dwelling or pre-owned dwelling).
Since October 2005 the ONS HPI (formerly the DCLG HPI) has been based on a sample of mortgage completions data from the Regulated Mortgage Survey (RMS) as collected by the Council of Mortgage Lenders (CML).
The number of transactions received from the RMS is affected by the total number of mortgages completed for house purchase in any period. During 2011 the sample covered 65-70 per cent of all UK mortgage completions.
The ONS HPI is mix-adjusted to allow for differences between houses sold (for example type, number of rooms, location) in different months within a year. House prices are modelled using a combination of characteristics to produce a model containing around 100,000 cells (one such cell could be first time buyer, old dwelling, one bedroom flat purchased in London). Each month estimated prices for all cells are produced by the model and then combined with their appropriate weight to produce mix-adjusted average prices. The index values are based on growth rates in the mix-adjusted average house prices and are annually chain linked. More information on the model used is available via the following link:
The ONS HPI is a weighted Laspeyres-type index. In January of each year the index weights are updated based on the relative numbers of transactions during the previous three years, which are grossed to total transactions obtained from Land Registry. Applying new weights ensures that the index keeps up to date with changes in the types of properties that are being purchased, and therefore reflects the price of the average property.
One consequence of changing the weights every year is that the mix-adjusted house prices cannot be compared between years as the weights are different. The index itself is constructed on a chain-linked basis, which enables year-on-year comparisons to be made. This means that the year-on-year change in the index for June 2011, say, is effectively the change in the average price from June to December 2010 (using the weights for 2010) combined with the change in the average price from January to June 2011 using the weights for 2011. Therefore, the year-on-year change in the index is not the same as the year-on-year change in the mix-adjusted average price. More information on the HPI methodology is available via the attached link:
Seasonally adjusted estimates are provided at a national level alongside the non-seasonally adjusted figures. Seasonal adjustment is performed each month and reviewed each year, using the standard and widely used software X-12-ARIMA. Seasonally adjusted house price estimates are used to report monthly percentage changes. All other figures such as annual rates of change and average house prices are based on non-seasonally adjusted estimates, unless otherwise stated.
The mix-adjusted house price index is a weighted average of prices for a standard mix of dwellings. From 1969 to 1992 the index reflected dwellings mortgaged by building societies. From 1983 the standard mix of dwellings was updated annually to reflect the types of dwellings purchased during the previous three years. In the early 1990s many of the larger building societies converted to banks and an index limited to building society mortgages could no longer be assumed to be representative of all house purchases. So from 1993 the index was extended to include both banks and building societies and was re-named the All Lenders index. It was based on a five per cent sample survey of all lenders. Since 2001 a number of lenders (but not all) submitted details of all their completions instead of a five per cent sample. Data from 2003 through to August 2005 reflects the results of this enlarged sample. From September 2005, the survey became 100 per cent for those lenders taking part and changed to take data from the Financial Services Authority data collection. Its name was changed to the Regulated Mortgage Survey (RMS). Data covering 1993 to 2002 are based on a sample size ranging from 26,000 to 36,000 per annum. From mid-2003 to August 2005 the survey covered about 25,000 mortgage completions per month. The RMS is larger and by the end of 2005 was covering about 40,000 mortgage completions a month. During 2006 about 50,000 mortgage completions a month were covered.
The questionnaire on which the survey is based has been revised from time to time, for example in 1982 when the question on the previous tenure of borrowers was extended to identify sitting tenants. The present method of analysis was introduced in the second quarter of 1968 and most of the detailed series now published have their origins in this period, although the mix-adjustment was modernised in 2003 when the monthly series was introduced.
At the end of every quarter, as well as releasing final figures for the latest month, ONS revises the figures from the previous two months. This is done because some mortgage lenders, which account for 1 to 2 per cent of all records, provide their data on a quarterly rather than monthly basis. Additionally, data will be revised for the previous month if more than 1,000 additional cases are received in a subsequent month.
Other revisions to historical data (other than those currently due for revision) will be made only if the revision is substantial.