It's probably not much of a surprise that property-obsessed Britain has at least five main indices measuring house prices.
Nationwide, Halifax, the Office for National Statistics (ONS), Zoopla and Rightmove all produce monthly data reports that record the ups and downs of property prices.
But their conclusions on the state of the housing market are all slightly different, which can make things a little confusing.
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So, how do the property indices differ from each other? We take a look at what each one measures and which house price index is the best.
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Nationwide house price index
The Nationwide house price index is one of the most popular indices used in the UK, with data stretching back to 1952.
The data used is based on the lender’s valuation at mortgage-approval stage. This may differ from the actual sale price, but the idea is that it is near enough to the end of the home-selling process to offer a more realistic snapshot than an initial asking price.
The index is mix-adjusted, which means it tracks a representative home by giving a relative weight to each property based on characteristics like the number of bedrooms. This prevents price disparities from arising if different types of properties are sold each month.
Halifax house price index
Halifax’s house price index has data going back to 1983 and, like the Nationwide index, is based on the bank’s valuation at the mortgage-approval stage.
A standardised house price is calculated using this data, and property price movements on a like-for-like basis are analysed over time.
Rightmove house price index
Rightmove’s house price index differs from Nationwide and Halifax in that it is based on asking prices.
The asking price is usually determined at the very first stage of the home-buying process. The index also excludes house prices across inner London.
One obvious advantage of using asking prices is that it picks up price trends early on.
However, one of the main issues with the Rightmove index is that it mirrors market sentiment rather than solid data, according to London estate agent Petty Son & Prestwich. There is also no guarantee that a house that's advertised will sell and, even if it does, the asking price can differ drastically to the eventual selling price.
Despite this, the house price report is useful for data on discounts and how quickly properties are going under offer, which gives a good indication as to the health of the property market.
Zoopla house price index
The Zoopla house price index uses sold prices, mortgage valuations, and data for agreed sales to calculate house prices for any given month. In other words, it tracks achieved prices, which is a key difference from an asking price index. Tracking homes that are “sold subject to contract” is a better indicator of current house prices, as the asking price often does not reflect the sale price.
The index also provides data on the number of days it takes to sell a house, giving prospective sellers a rough idea of how long it will take for their property to sell. This measures the time from the initial listing to going under offer.
Unfortunately, Zoopla’s index, like all other indices on this list, relies on a limited pool of data with some degree of time lag.
ONS/Land Registry house price index
Each month, the Office for National Statistics calculates official house price figures using sale data from HM Land Registry, Land and Property Services Northern Ireland, and Registers of Scotland.
The ONS index uses a statistical method called hedonic regression that adjusts the data to account for characteristics like the number of bedrooms.
Unlike the Halifax and Nationwide indices, which are based on mortgage approvals, the ONS data also includes cash purchases. This gives a broader view of the market and therefore, arguably, makes the index the most authoritative of the big five.
One downside is that the index has a time lag of around two months, as it takes some time to process conveyancers’ submissions to the Land Registry after a sale is completed.
This means the index is the least contemporaneous out of the five major indices.
UK Residential Market Survey by RICS
The UK Residential Market Survey by the Royal Institution of Chartered Surveyors (RICS) is very different to all other indicators in this list. It is a well-respected monthly sentiment survey of chartered surveyors operating in the residential sales and lettings markets.
Surveyors are asked to answer 18 questions on whether various metrics, such as sales, enquiries, listings, and house prices have risen, remained the same or decreased.
While it doesn't provide an average house price for a specific month, it serves as an indicator of current and future conditions in the UK housing market.
A positive net balance indicates that more surveyors are observing price increases, signalling a strong housing market. Conversely, a negative net balance suggests that more surveyors are witnessing price decreases, indicating a more fragile housing market.
For instance, if 15% of surveyors reported an increase in buyer inquiries and 20% reported a decrease, the net balance would be -5%.
