Finding out how much a property is worth is crucial for an investor trying to do some sums to check out if the rent and yield stack up against the asking price.
Several property firms, lenders and government departments publish monthly house price surveys, but their results are questionable.
The big factor that is causing most confusion is the size of samples.
Back in 2007, at the height of the property bubble, more than 100,000 homes changed owners every month. Now that flood is down to a trickle of 50,000 or less homes.
That makes some of the sets of data house price surveys the number crunchers base their figures on more or less useless.
The most reliable data comes from the biggest sample – which would be the Land Registry database of completed sales.
Three house price surveys are based on this information – the Land Registry's own survey; an index published by the Communities and Local Government Department and another by LSL Property Services, a large estate agency chain.
House prices are out-of-date, biased and useless.
Even then, the data has problems – it's out-of-date because the Land Registry has to wait for lawyers to file title papers to compile the figures. This can mean a month to collate the figures and another month to run the analysis.
Then, the Land Registry offers 'average' house prices both regionally and nationally - that is if you accept national means just England and Wales. Of course, no one lives in an average home, so the comparison figure is useless.
The headline price guides from lenders the Nationwide and Halifax grab most attention. Their reliability is based on the market share of those lenders and the home loans they offer – not the just the ones that go ahead.
This means they are biased to areas where these lenders have their largest customer base that are not necessarily representative of the whole market.
Online property portals like Rightmove, Zoopla and Findaproperty offer figures based on asking prices that are inflated and often well adrift of actual sale amounts.
The government has proposed a single, official house price survey for the whole UK. So far, the working party has looked at the proposal for around six months without hinting at a solution.
Meanwhile, putting a price on a home remains a lottery.
