Tuesday 20 October 2009, 11:12
As Michael Blastland teaches elsewhere on CoJo - beware of counting methods.
Before the postal workers' strike ballot, The London Review of Books carried an intriguing 'diary of a postman' - called Roy Mayall (beware of naming methods, too, perhaps).
It may or may not be the experiences of a single postie; it's certainly an account by someone who knows the business of sorting offices and rounds well.
But this is the thing that caught my attention. An account - I can't verify it - of the numbers underlying one of the central claims in the dispute. That the volume of mail is decreasing - the figure of 5.5% over the past year is cited and a 10% decrease predicted for the coming year.
Should a journalist take that figure on trust? Well, on the basis that no journalist should ever take any figure on trust, no. Of course not.
But take a look at this - 'Roy Mayall's account of how that decline is calculated:
"The truth is that the figures aren't down at all. We have proof of this. The Royal Mail have been fiddling the figures. This is how it is being done.
Mail is delivered to the offices in grey boxes. These are a standard size, big enough to carry a few hundred letters. The mail is sorted from these boxes, put into pigeon-holes representing the separate walks, and from there carried over to the frames. This is what is called 'internal sorting' and it is the job of the full-timers, who come into work early to do it. In the past, the volume of mail was estimated by weighing the boxes. These days it is done by averages. There is an estimate for the number of letters that each box contains, decided on by national agreement between the management and the union. That number is 208. This is how the volume of mail passing through each office is worked out: 208 letters per box times the number of boxes. However, within the last year Royal Mail has arbitrarily, and without consultation, reduced the estimate for the number of letters in each box. It was 208: now they say it is 150. This arbitrary reduction more than accounts for the 10% reduction that the Royal Mail claims is happening nationwide.
Doubting the accuracy of these numbers, the union ordered a random manual count to be undertaken over a two-week period in a number of offices across the region. Our office was one of them. On average, those boxes which the Royal Mail claims contain only 150 letters actually carry 267 items of mail. This, then, explains how the Royal Mail can say that the figures are down, although every postman knows that volume is up. The figures are down all right, but only because they have been manipulated."
Whether this account is true or not, it's an excellent illustration of what should be standard journalistic practice: when you're faced with a number, ask how it was arrived at.