Evidence and the persistence of mistaken ideas: the case of house prices

Another paper, this time from the Bank of England written by former MPC member David Miles and Victoria Monro, shows that the rise in house prices we have experienced since 1985 is mainly the result of lower real interest rates. The other, less important, driver is household income. Those two effects together can account for all the increase in house prices relative to inflation. The increase in house prices is not the result of a shortage of new houses.

Those who remember two earlier posts of mine will know of my own conjecture along similar lines. More recently Ian Mulheirn has championed this theory: here he is commenting on an apparently contrary view from Paul Cheshire. The importance of real interest rates to house prices has been understood for a long time: the first time I came across it was when Steve Nickell wrote a paper when I think he was still on the MPC. Very recently, here is Paul Johnson making the same point.

Secular stagnation is used by most macroeconomists to describe the current era where real interest rates appear to be permanently lower than they were decades before. The uncomfortable conclusion would be that as long as this era lasts, house prices will remain at levels that are unaffordable for many young people. Building more houses on any reasonable scale is not going to change that very much.

The reasoning behind the theory is incredibly simple. Houses are an asset. Like any asset, its price depends on the return from holding them (in the case of housing rents) and the rate of interest. The demand and supply for housing services (i.e. a roof over your head) determines rents rather than house prices. Imagine choosing between investing in housing or in government debt (more specifically a perpetuity, so you never get the money back but the interest pays forever), Interest rates on government debt are 2%, so on every £100 K you invest in government debt, you get 2K a year in interest. Suppose the (net of costs) rent on every £100K of house was 2K a year. Then you are indifferent to whether you own either asset.

Now suppose interest rates fall to 1%, but rents stay the same. Everyone wants to become a landlord, and people with money to invest buy houses to rent, because before interest rates rose you are getting double the return you were getting on debt. With perfect arbitrage this will carry on happening until houses that used to be worth 100K are now worth 200K, so that the return to housing again equals the return to holding debt = 1%. House prices have doubled, but the demand and supply of housing services has remained unchanged. The suggestion is that this is the process behind rising house prices in the UK.

That does not mean building more houses (increasing the supply of housing services) has no effect on house prices. Raising supply pushes down rents, other things being equal, and that reduces the return from owning a house, so it will reduce house prices. But the stock of houses is very large, so even with large house building programmes the impact on rents is small. Here Ian Mulheirn shows what the paper by Miles and Munro says about the small size of that effect.

You might say that any reduction in house prices is welcome, but you are using a great many resources (and a fair bit of land) to produce a modest effect. You might get a similar impact on house prices if the government undertook a serious fiscal stimulus, leading to a rise in short interest rates which would have a modest impact on long interest rates, but a noticeable impact in reducing house prices.

My question is why this point is almost never made in the popular discourse on the house price problem? One answer is that housebuilders have a vested interest in suggesting a dire need for more housebuilding, in part because it adds to pressure on governments to free up greenfield sites. This is exactly what has happened since 2010. There is nearly always a vested interest in perpetuating incorrect economic explanations.

In this case, as in others like the supposed need for austerity, there is something else, and that is an apparently simple piece of economics that perpetuates this misconception. With austerity it is that the government should be like a household, which most economists believed before Keynes showed it was false. With house prices it is that prices reflect demand and supply.

The difference between austerity and failing to distinguish between house prices and the price of housing services is that the former is more difficult to challenge than the latter. The reason is that everyone also talks about housing normally being a good investment. That is seeing housing as an asset, so all you need to do to break the misconception is a bit of asset pricing theory.

With issues like these, there are two spheres of understanding, with precious few links between them. There is what I will call the knowledge sphere, where academics (including academic think tanks) and economists in central banks and elsewhere regularly exchange ideas and evidence within that group. There is a second group comprising most of the print media, the broadcast media, some (mainly right wing) political think tanks and most politicians, where again communication within the group is pretty good. 

Communication between the two spheres is sparse. Most political journalists in the broadcast media spend more time watching each other and reading the print media than they do talking to people in the other sphere. Despite many who work hard to package knowledge in accessible ways, often the best those in the knowledge sphere can hope for is an article in the Guardian, FT or Times. If politicians don’t want to access expertise, there is therefore little requiring them to be knowledgeable. The examples I have highlighted are from economics, but I think it is true for all the social sciences.

As a result, politicians can continue to propagate and pursue bad ideas, like austerity is necessary or house building is the answer to high house prices, with little or no challenge in their own sphere. This is not about experts forcing politicians to do what they suggest, but about the public and even politicians being aware of what the evidence suggests. The fundamental problem is not that those in the knowledge sphere don't communicate well, but that too many politicians and much of the media do not want to be well informed.