Amid an undisputed housing boom which is expected to last for many years, there's drumbeat of complaint that people can't afford houses, that inflation is forcing families to buy less desirable homes than used to be available.

Are homebuyers acturally worse off today than they have been in the past? The answer to that question is important to all of us, not just to homebuyers. If enough people decide that housing is in fact harder to get, Congress might pass a housing aid program that would cost a lot of tax money.

A recent study by Robert Gough, senior research economist at Data Resources Inc., throws some fascinating light on what the money problem really is. Many of the things about housing that we have all assumed to betrue apparently are not. For example:

We tend to think that the median price of a new house today is sharply higher in relation to median income than it used to be. But in fact, the price of new houses relative to median income is lower than it was in 1955 and about the same as in 1960 and 1965. But the value is better, since today'snew homes are generally larger and better equipped.

We tend to assume that new house prices have risen at a sharply higher rate than median income. But over the past 20 years, incomes have risen 235 per cent and new house prices 223 per cent. The price of older houses has risen 220 per cent. In other words, on a long-term basis, rising incomes have exceeded rising house prices. (House prices have risen faster than incomes in the past three years, but Gough thinks that's a temporary phenomenon.)

We tend to assume that a median-income family should be able to afford a median-priced house.But that has almost never been the case.

In 1955, 1960 and 1965 - as in 1976 - the median price was about three times higher than median income, which generally put the house out of buying range. (The rule of thumb is that you can't afford a house that costs more than two-and-a-half times income.) The median price of an older house, however, has always been within the buying range for median-income families. The price of older houses today is about the same in relation to income as it has been for the past 20 years.

If all this is true, then what's happening today? Why are families feeling pinched in their housing choices? Two reason.

First, higher interest rates have pushed monthly mortgage payments up sharply. From 1955 to the early 1970s, median monthly payments were around 16 to 18 per cent of median income. But in 1975 and 1976, payments ran around 22 per cent. So although a particular house may be within your traditional buying range, the monthly mortgage payment may now be higher than you can swing on your income. Interest rates (and taxes) are the real villian, not new house prices.

Secondly, the years between 1965 and 1970 were unusually prosperous. The set-up in Vietnam war spending inflated the incomes of workers, but had not yet started to drive up prices in a serious way.