This guidance highlights the differences between the Scotland figures within the UK House Price Index (HPI) and our house price statistics.
For more information about how we compile our statistics, see our guidance notes.
Summary
The headings below provide an overview of the differences between the methodology and content of the HPI and the methodology and content of the quarterly statistics.
Frequency of publication
House Price Index: Monthly
RoS house price statistics: Monthly, quarterly, calendar year and an annual report based on financial year.
Base data source
House Price Index: Applications for registration in the land register, plus house types derived using RoS methodology and base mapping data (Ordnance Survey ©Addressmap)
RoS house price statistics: Based on applications received for registration in the land register.
Date range of extraction
House Price Index: Based on the date of entry to the property for each calendar month
RoS house price statistics: Based on applications received for registration in the land register within each quarter
Price range
House Price Index: All data with a consideration
RoS house price statistics: £20,000 to £1 million
Average house prices
House Price Index: Based on geometric mean – sub-Scotland local authority figures will be based on three-monthly moving averages to reduce volatility
RoS house price statistics: Based on arithmetic mean and median
Case mix adjustment
House Price Index: Yes – based on room numbers provided via EPC data
RoS house price statistics: No
Seasonal adjustment
House Price Index: A separate seasonally adjusted series is available, calculated at the regional and national level only
RoS house price statistics: No
Revisions
House Price Index: Three-month cycle – final figures at three-month update
RoS house price statistics: Entire time series revised for the majority of our statistics and users should use the complete time series in the latest available statistics
Volume of sales
House Price Index: Yes
RoS house price statistics: yes
Property types
House Price Index: Yes – detached, semi-detached, terrace, flat
RoS house price statistics: Yes – detached, semi-detached, terrace, flat
Cash sales
House Price Index: Yes
RoS house price statistics: Yes, identified separately in calendar year tables and property market report.
New builds
House Price Index: Yes
RoS house price statistics: Yes, identified separately in calendar year tables and property market report.
Buyer analysis
House Price Index: Yes – statistics relating to first-time buyers and former owner-occupiers is extracted from CML data
RoS house price statistics: First-time buyers and former owner-occupiers are included but not separately identified
Results
House Price Index: Average prices presented as geometric means are typically closer to the median than the arithmetic mean
RoS house price statistics: Typically the use of an arithmetic average will lead to a higher price than the use of other measures. This is because an arithmetic approach to calculating the average price takes full account of the extreme value properties that have been sold. As a result, the average price can be sensitive to high-value property
Average prices
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The average price trends when comparing the HPI with our house price statistics are very similar. There's a slight delay to changes in our figures, because our data is based on the date of registration, while the HPI is based on the date of entry. Registration can occur up to several weeks after the date of entry.
Quarterly and monthly averages are higher in the RoS statistics than in the HPI. This is expected because of the different methodologies used - specifically, the use of an arithmetic mean within the RoS statistics, versus a geometric mean in the HPI. The geometric mean will typically be closer to the median than the arithmetic mean.
The HPI monthly figures are smoother than the RoS monthly house price statistics, again because of the different methodologies used. The HPI figures are mix adjusted, while the RoS house price statistics use the mean of all sales between £20,000 and £1 million. This means the RoS figures are more prone to fluctuations in the market, for example if a high number of high or low-value sales are registered within a particular month.
On average, the HPI house price averages are 15.5% lower than RoS monthly house price averages. The difference ranges from 5.2% to 28.4% lower than RoS stats.
Volumes
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Again, the volume trends when comparing the HPI with RoS house price statistics are very similar. There are slight differences in the volumes being presented because the RoS data is based on date of registration, while the HPI is based on date of entry. Overall, across the period shown, the difference between the volume figures was less than 1%.