Median or average: which HDB price should you believe?

“The average HDB price” is two different numbers wearing one name. When a headline says average it usually means the mean: add every price, divide by the count. When this site says median it means the middle resale: half came in above, half below. In a large calm market the two sit close. In a single town in a year when a handful of million-dollar flats transact, they do not.

Why the mean drifts

The mean uses every dollar of every sale, so one exceptional transaction moves it. A town that trades a few hundred flats around $550,000 plus a dozen resales above $1.2 million gets a mean well above what a typical buyer paid. Nobody bought at the mean. The median barely notices: the middle sale is still the middle sale.

Singapore has made this concrete over the past few years. Million-dollar HDB resales went from a curiosity to a regular occurrence, concentrated in a small number of towns and blocks. Every one of them pulls a mean upward and leaves a median almost untouched, which is exactly the behaviour you want from a headline figure.

Where the median is weak

It is not a free lunch. A median throws away information about the tails, and the tails are where the interesting flats are. That is why the town pages here also publish the 20th and 80th percentiles, and a full distribution chart: the median is the headline, the spread is the context, and the individual resales are underneath both. Compare Bishan and Sengkang and the medians tell you one thing, the spreads tell you another.