Talking about the sensitive issue of immigration, Conservative MP Bernard Jenkin said ‘Most people would be utterly astonished to learn that there is no attempt to count people as they enter or leave the UK'.
Should we be shocked, worried, disappointed or just accept that realistically it would be too expensive and too difficult to find out the numbers?
We can find out almost anything if we design a suitable system and we are prepared to pay for it. We will always have to accept that there will be a margin of error – but how much is acceptable?
When it comes to actual votes cast in an election, how accurate are these? Exact results are recorded down to the last vote. These figures are pretty accurate, but when there is a re-count, the new result does not always (or even usually) tally exactly with the first count. Human error plays a part. I have been an observer at election counts and in a two-hour session I spotted two wrongly-allocated ballot papers. In this case it would not have mattered because the errors would have cancelled themselves out, but I was just one observer among about 12 and only for part of the count, so a small margin of error is likely to exist. Fraud, is rare, but not unknown, in British politics. Another reason for doubt about the exact figures is the number of spoilt or dubious ballots, where voters have written on the paper, identified themselves or put a cross which is not completely in one box. Normally the candidates agree on which papers should be counted, but it is not an exact science. But, most people would agree that election results are a fair reflection of the votes cast.
Most people are happy that opinion polls based on a sample of around 1,000 voters are accurate enough to give an idea of the relative positions of the parties and over time they can give a view of trends in support. 95% of the time the figures for party support will be within a margin of 3% of the figure reported. Given the cost of opinion polls, most people would rather have them as an affordable estimate of party support, rather than go without.
For crime figures we have police records and surveys conducted among a sample of the population. Since the figures, arrived at in completely different ways by different organisations, usually tally fairly closely, we can believe that they are a good indication of general trends in crime.
Every 10 years we have a very expensive census, designed to provide an accurate snapshot of the population. I worked on the 2011 Census and the workers were carefully selected, well-trained and the forms and systems were well designed. Households were asked to return their forms by a certain date and then collectors went to all the addresses where no form had been returned. The collectors went back perhaps as many as eight times to some addresses and where no answer could be obtained, neighbours, estate agents and other sources of information were used to try to find out if someone lived there. However, even with this well-designed and expensive exercise, if a householder was deliberately trying to give false information, they were quite likely to have gone unnoticed. The exercise relied on honesty. Most people are honest, but not all.
So, for most practical purposes we have figures which we can be confident are accurate enough for decision-making, not ridiculously expensive to gather and that we have some idea of the limits of their accuracy.
When it comes to the delicate issue of immigration, we could reasonably expect, with all the border checks at air and sea ports, that a pretty close eye is kept on the numbers of people entering and leaving the country. In this context, Bernard Jenkin’s comment that ‘Most people would be utterly astonished to learn that there is no attempt to count people as they enter or leave the UK’ is a valid one. I count myself among the astonished. A major part of the system for counting, or in this case estimating, the numbers of people coming and going from the UK is the International Passenger Survey, which was designed in the 1960s to track tourism, based on random interviews with a sample of travellers. According to the Public Administration Committee, chaired by Jenkin, only 5,000 migrants a year are identified through the survey. Most of the rest of the figures are estimates extrapolated from the survey and with a large (and unknown) margin of error.
Astonished – I think we should be. Would we be happy to know that a football match ended roughly as a draw?..that a cricketer scored somewhere between 97 and 103?..or that Andy Murray was somewhere in the top two or three at Wimbledon?