Inflation is meant to creep up, but sometimes it comes bounding up and bites you. Just ask anyone trying to make new child-care arrangements.

Officially, we are still in a low-inflation economy. The Consumer Price Index shows an increase of just 2.5 per cent between April 1997 and April this year. The economists in the Central Bank and elsewhere have been worrying about rises in inflation driven by intercontinental ballistic house prices for the past two years and more, but nothing much has happened to the general level of inflation. But there are "pockets of inflation". Child-care costs are a salient example. Anecdotally, one hears about creche facilities now costing £100 per week per child when they would have been £80 per week last year. That is an increase of 25 per cent. Recruitment agencies for home child minding will tell you that wages being paid to childminders have increased by 2540 per cent in the last year. Carmel Carolan of Small World Recruitment says that wages have gone up from about £110 to £120 per week to at least £140 to £150 per week and more. Parents now need to be prepared to pay £180 to £200 per week for a "live-in" child-minder. Mary Breslin, of Breslin International Recruitment, says that the boom in child-minding costs has really taken off since about September of last year and speaks of around £170 per week for new child-minding jobs.

She warns that child-minders should not look at price alone when deciding which job offer to accept, but says it is very difficult to focus on how you'd get on with the parents and children when families will bid up to attract you. There is a contraction of supply of child-minders and an increase in demand at the same time, evidenced by the increase in the number of women at work shown in this week's Central Statistics Office figures. Hence, price rises.

None of this is to suggest that child-minders do not deserve good wages and good conditions, whether they work in homes or daycare centres. It is about the experience of real costs versus official, average figures.

So, what of the Consumer Price Index? One would imagine that an increased cost, which in many people's budget vies with food as the second largest item after mortgage repayments, would have an effect on the CPI. Not so.

The CPI is based on the five-yearly household budget survey, calculating what the average household over the entire State spends on various items. A weight is assigned to each item or group of items and actual increases in their prices, or some of them, go into the new CPI statistics each month.

The cost of child-minding in a creche comes into the CPI under the general heading of education and training. Education and training is given a weight of just 1.0685 per cent of the total CPI. By contrast, tobacco has a weight of 4.82 per cent. If you pay for a creche, your household budget bears no resemblance to this or else you smoke well more than 100 packets a week.

This is not the fault of the Central Statistics Office, it's just the way averages can be meaningless to those who are not the average.

Still, it is telling that CSO education and training prices have gone up by 7.2 per cent in the last year, and, within that, child day-care and creche facilities (which do not include home child-minding) have gone up by 9 per cent in the year. Play schools have gone up by 12 per cent. The CSO is capturing increases, albeit not as dramatic as the anecdotal ones. But the price of home child-minding is not monitored monthly at all. The CSO assumes that it follows the price changes for creches and day-care centres.

It is given a weight in "other services" (up 6.5 per cent), along with items like ear piercing and watch mending.

The key point is that all types of child-care costs are well above the general inflation rate of 2.5 per cent. Even disposable nappies are up 8 per cent in the year.

Child-care costs are a potent political issue ready to explode. Look who is affected. The young couples, the middle class, the first-time house buyers already getting hit with property price rises, urbanswing voters.

Their home inflation rate is showing nothing like a benign increase of 2.5 per cent. If the second or third largest item in the budget is growing by between 10 per cent and 20 per cent, they are basically getting whacked, while official celebrations of low inflation continue.

And by the way, the CSO also shows that that first item, mortgage interest payments, across the entire spectrum of mortgages, old and new, have increased by 10 per cent since last April. For many families, it's a double whammy.

The Celtic party is getting a little rowdy for comfort.