, it turns out, is a measure of inflation and it’s how the interest rate on student loans is calculated. In short, it is the rate at which the price of things – like housing costs – rises. It’s also used to calculate train fare increases. But it’s fallen out of favour
with some economists as a way of determining increases because it doesn’t account for the fact that, these days, consumers will change to a different provider if prices rise. And as we all know, house price inflation is completely unhinged from the rest of the economy now. I did not learn this at school or university. Unless you studied economics, the odds are that you didn’t either.