How we compile our statistics

Registration

The house price data extractions come from information supplied to RoS with new applications to register a house sale. Registration occurs when a transfer of title takes place, regardless of the amount of money involved. As part of the registration process an applicant's agent (usually a solicitor) records the ‘consideration’ for which the title has been reassigned. It is possible for the consideration to be nil or below the true market value of the title. In such a case the applicant's agent (or solicitor) notes the basis of the consideration and also provides a value. Below market price transactions such as these are excluded from the statistics.

The registration process will also provide property address details, date of entry to the property, registration date, title number information, land class, deed type, buyer and seller information and details of any applications for registration of a mortgage over the property. RoS can therefore use the information gathered to identify residential sales, cash sales and new builds and the geographical location of the property.

Land class

RoS records six land classes: residential, commercial, land, agriculture, forestry and other. The land class information is provided by the submitting agent on the RoS application form when an application for registration is submitted.

Only residential sales are included in the data extractions for the HPI and RoS house price statistics (although the property market report includes a section on non-residential transactions).

As part of our data validation RoS reclassifies properties where the land class is incorrect, for example commercial premises that have been classified as residential.

Cash and mortgage transactions

Every deed submitted to RoS for registration is classified by deed type. It is possible, therefore, to identify if an application for registration of a mortgage security is received at the same time as, or in the weeks following, an application for registration of a residential sale.

A cash sale is defined as a residential sale for which no mortgage application has been received either at the time the sale is registered or within the period of up to 100 days following the registration of the sale. For example, if an application for registration of a residential sale with no mortgage security deed is received on 20 January and no application for registration of a mortgage security is received in either January, February or March, then the sale is classed as a cash sale.

As the HPI is based on the date of entry rather than the registration date, a deed received for registration in January could have a date of entry in December or earlier. Our revision process means that a property received for registration on 20 January, but with a date of entry in December, is added to the revised data for December and published in March. The cash sale status of this property is then updated in the April publication but is not updated again

New builds

The majority of new build properties are sales of plots from a builder’s title. RoS can therefore identify sales from major builders’ titles and flag them up as new builds. These sales are subject to a quality assurance process. The figures are likely to include the majority of new build transactions undertaken, but will exclude sales related to very small developments or single new build properties by private or small-scale builders.

Analysis by region

Properties are allocated to local authority area through use of a grid reference applied to an automated Geographical Information System. As a result of incomplete, or wrong, grid references, a small number of properties cannot be allocated to a local authority area. The HPI will exclude these unallocated properties from the analysis, while the analysis within the quarterly statistical release identifies these separately as "Unallocated".

Data validation and records excluded from analysis

Prior to producing the data extractions for the HPI and RoS house price statistics, a validation check is carried out on the database of registrations and the following actions are taken:

• Registrations in which the Consideration is less than the Value are identified so that they can be excluded from the extractions. This ensures that the analysis excludes registrations which are not true, market value sales, for example the sale of part of a title to a residential property which may occur when one of the joint owners of a shared property buys out the share of the other owner.
• The land class provided is compared manually with the address data with the aim of ensuring correct classification of residential properties.
• Sales of multiple properties in one application are identified so that they can be excluded from the extractions.
• Duplicate lines of data are identified and removed.
• Dates of entry are checked for obvious errors and missing dates of entry added.
• Any blank fields within the data are identified and populated if appropriate.
• All considerations under £20,000 and in excess of £750,000 are checked for accuracy.
• Right to buy sales of council houses to sitting tenants are included in the final RoS statistics, but the quality assurance aims to identify sales of blocks of properties and sales that are not true, market value sales, e.g. transfers of ownership between family members, sales of pro indiviso shares, etc, so that they can be excluded from the extractions.
• Applications which are subsequently cancelled are identified so that they can be excluded from the extractions.
• Foreign currency considerations are identified so that they can be excluded from the extractions.

Summary of house type methodology

Assignation of house type to sale

The house type is identified by using a house type classification system developed by RoS. RoS registers all residential property sales in Scotland, and we initially assign one of the four house types using Ordnance Survey (OS) mapping and address products.

The RoS methodology automatically classifies dwelling types according to the four pre-defined types and uses counts of addresses and neighbouring building polygons to classify each property. This method of classification is detailed in the table below.

House type		Example	Method of classification
Detached			A building with no adjacent addressed building.
Semi - Detached			A building with 1 adjacent singly addressed building.
Terraced House			A building with one or more singly addressed neighbours.
Multiple Occupancy			Any building with 2 or more unique addresses in any single building.

The majority of house types can be identified using the above method to an accuracy rate of 96.4%. When all sale applications have completed the registration process, the house type can be assigned to one of the four house types by this method.

Revision policy

The revision policies for statistics from Registers of Scotland are outlined below:

• Monthly statistics: each month, revisions made to the entire time series, from April 2003 to the latest data period.
• Quarterly statistics: each quarter, revisions made to the entire time series, from 2003-04 Q1 (April to June 2003) to the latest data period
• Calendar year statistics: each quarter, revisions made to the entire time series, from 2004 to the latest complete calendar year
• Property market report: revised annually, full financial year time series revised. These statistics differ from other RoS statistics as they have been extracted from a live database at a different point in time and are not subject to scheduled revisions throughout the year. The data in this publication, therefore, may not always be the most up-to-date
• Land and property titles by country of origin: annual snapshot of the Land Register so no formal revision process. Annual snapshots from one year to the next are though subject to changes made in the live Land Register database

Revision policy for the UK HPI

Registers of Scotland house price statistics are based on administrative data derived from applications for registration on the Land Register. This data from the Land Register System (LRS) is live and subject to constant change. As a result, for the majority of our statistics the entire time series is revised and users should use the complete time series in the latest available statistics.

As the RoS house price statistics are extracted based on date of registration – the date that the application was received for registration – rather than date of entry, changes in updated transaction volumes are predominantly from the cancellation of sales rather than the inclusion of additional transactions. For this reason the general movement in updated volumes is downward but the overall effect is not sufficiently large enough (or to alter interpretation of the statistics) to put in place formal scheduled revisions.

A provisional label, however, is applied to the latest monthly statistics and latest statistics by house type included in our quarterly, calendar year and property market report statistics.

The latest house type statistics included in the quarterly, calendar year and property market report statistics are labelled provisional. For the quarterly house type tables, a provisional label is applied to the latest eight quarters. For the calendar year house type tables, a provisional label is applied to the latest two complete calendar years. For the property market report house type tables a provisional label is applied to the latest two financial years. The provisional label is used because of the number of sales that cannot be assigned to a house type. Residential property sales are assigned to one of the house types through a GIS-based classification system developed by RoS. For the latest statistics, a substantial number of sales cannot be assigned to a house type. This is primarily due to time lags between a title bein

received for registration and the updating of the map base. The long-term average proportion of sales that cannot be unassigned is 3% in a financial year. However, the proportion of unassigned sales increases for the most recent statistics (8% in 2023-24 and 6% in 2022-23). A provisional label, therefore, is used to caution users when using the latest statistics given the number of sales that remain unassigned.

Other revisions (ad-hoc or unscheduled corrections)

Ad-hoc revisions, for example methodological improvements, or unscheduled corrections owing to identification of errors may occur from time to time. Our approach to such revisions will be in line with the Scottish Government’s revision policy and the Code of Practice for Statistics. Particular attention will be paid to the scale, nature, cause and impact of the changes, and users will be notified as soon as practicable.

For further details on our methodology, get in touch by emailing data@ros.gov.uk.

Footnotes

1. HMLR, Registers of Scotland, Land and Property Services Northern Ireland (LPSNI), Office for National Statistics (ONS)↵
2. Hedonic regression is widely used for estimating house prices. For a hedonic regression the properties are defined in terms of a set of features or characteristics, each of which contributes to the value of the property. For example, the number of bedrooms or the location of the property will contribute to its value, but these features cannot be priced in isolation. A regression model is used to estimate the value of each of these features from the set of properties sold during a particular period. For example, the model might estimate the effect that every additional bedroom and each different location have in the sale price in a certain month. Then, the price of a particular property can be calculated by combining the values assigned to each of its features.↵
3. Data provided from CML.↵
4. There are different ways of calculating average prices. These include the arithmetic mean, the geometric mean and the median. The geometric mean involves multiplying the prices together, and then taking the cube (third) root of the total. An arithmetic mean, where all the prices are added up and divided by the number of sales) can result in those areas with the highest priced properties tending to dominate the index, whereas the geometric mean is more equal in its weighting of the change in price of expensive and cheaper properties.↵
5. Building polygons are building shapes identified on the OS digital map base.↵
6. An “address point” is a point marker used to identify an address within a building on the OS basemap.↵
7. A “Title seedpoint” is a point marker used to identify the position of a Land Register Title on the OS basemap.↵