My troubles began while I was tidying up my CD collection, the decaying fruit of a misspent youth. I don’t mean alphabetising it, merely sorting through the piles of scratched silvery discs and putting them back into their cases. The process reminded me just how much music I don’t listen to, simply because of the archaeological dig that would be required. And so I started to think of copying all this music into some wonderful electronic box, and chucking the CDs away.

After a bit of research, I now realise that I have a dizzying range of choices – media PCs, iPod docks, dedicated music servers and wireless “bridges”. Don’t ask me to begin to enumerate the pros and cons, although it seems clear that most of them do things with music that it would have been hard for most of us to imagine 10 years ago. The human response is bewilderment. The economist’s response, of course, is “I wonder how many of these gizmos are in the inflation statistics?”

When I was a boy, there were no CDs. (The CD is 25 years old this year; The Visitors, by Abba, was the first one produced.) The original CD players were ludicrously expensive, so not many people bought them. Only when the price came down did people embrace the CD format.

That makes things difficult for the bean-counters who compile the inflation statistics. The Office for National Statistics (ONS) sends surveyors out to the shops once a month; the surveyors take a note of the prices; someone at the ONS adds up all the prices, and we see how much inflation has taken place in the past month. CD players have been falling in price and improving in quality for years, which should show up as a contribution to lower inflation.

But it is precisely when the price falls and quality improvements are most dramatic that they make little or no impact on the inflation statistics. That is because when CD players were scarce, the ONS did not collect CD prices. Only this year did they start collecting the prices of modern marvels such as small flat-panel televisions, digital radios and digital-photo processing.

When such new goods appear, the inflation statistics do not acknowledge their existence, and only do so when their price has fallen and quality has risen enough to make them widely adopted. When prices are falling most steeply, people are not yet buying in bulk and the ONS is therefore not yet including the new goods in its monthly survey.

The ONS already collects 120,000 separate price quotations (representing 650 consumer goods and services in many different locations). If they had more resources, they could collect more, but it would not change the fundamental difficulty. New goods would still be given a tiny weight in the calculations until they became mass-market products.

It’s a special case of a more general problem in collecting inflation data: a change in the price of brie shows up in the inflation figures only if we spend a lot of money on brie. But one of the things that determines whether we spend money on brie is of course – the price of brie. Price changes affect what we buy, what we buy affects how statisticians compute price changes. (Jamie Oliver probably has an effect, too. Brie is out of the ONS survey this year; olive oil is in.)

Don’t blame the ONS. To calculate how much inflation has taken place over the past 50 years, it would have to show how many gramophones are equivalent to an iPod. The problem is unsolvable, and if you disagree, may I recommend that you write directly to the ONS. On the other hand, if you can tell me how to deal with my CD collection, I am listening.

Tim Harford is author of ‘The Undercover Economist’