Regress and progressMar 8th, 2009 | By Ian Poulton | Category: Ireland
One evening, driving through an area dominated by paramilitaries, with lurid murals on gable ends and kerbstones painted red, white and blue, there was encouragement on the radio. The man on the radio said the place would not always be as bad as this, that it would improve.
Of course, the man said nothing specific, he did not say that this estate would change, that people would become law abiding, that standards of living would improve. No, he wasn’t specific, but what he did talk about was something called ‘regression to mean’, the tendency of things to move back towards the long term average. Had the studio discussion been applied to practical situations, regression to mean in that estate would presumably have meant a shift towards long-term averages in human behaviour, which would mean less gangsterism and greater affluence.
We live our lives believing in regression to mean; if it did not happen we would be asking questions about interference and fairness. Spin a coin and it’s as likely to come up heads as tails. There might be sequences of one or the other, but a chart showing the sequences, with tails in one direction an heads in the other, would show most of the sequences clustered around the middle, those are the rules of chance. Were we to encounter a sequence like that of Rosencrantz and Guildernstern, we might have serious questions about the world, physics, or the honesty of the other person:
Guildenstern takes another coin, spins it, catches it, turns it over on to his other hand, looks at it, and throws it to Rosencrantz who puts it in his bag.
Guildenstern tales a third coin, spins it, catches it in his right hand, turns it over on to his left wrist, lobs it in the air, catches it with his left hand, raises his left leg, throws the coin up under it, catches it and turns it over on to the top of his head, where it sits. Rosencrantz comes, looks at it, puts it in his bag.)
Rosencrantz: I’m afraid –
Guildenstern: So am I.
Rosencrantz: I’m afraid it isn’t your day.
Guildenstern: I’m afraid it is.
Guildenstern: It must be indicative of something, besides the redistribution of wealth. (He muses.) List of possible explanations. One: I’m willing it. Inside where nothing shows, I’m the essence of a man spinning double-headed coins, and betting against himself in private atonement for an unremembered past. (He spins a coin at Rosencrantz.)
Guildenstern: Two: time has stopped dead, and a single experience of one coin being spun once has been repeated ninety times… (He flips a coin, looks at it, tosses it to Rosencrantz) On the whole, doubtful. Three: divine intervention, that is to say, a good turn from above concerning him, cf. children of Israel, or retribution from above concerning me, cf. Lot’s wife. Four: a spectacular vindication of the principle that each individual coin spun individually (he spins one) is as likely to come down heads as tails and therefore should cause no surprise that each individual time it does. (It does. He tosses it to Rosencrantz)
If, in the long run, the average number of heads is going to match the average number of tails, if in the long run the highs descend to the average and the lows rise, then regression to mean should be embraced. It means the economy will rise from the trough into which it has sunk back towards a long-term average.
Confidence that things will improve is no consolation to the hundreds of thousands trapped in the pain of the current downturn. A fair and just society cannot be content simply to regress; we must ask questions on how to progress; how to ensure that the coin comes up enough times on the right side to compensate for the many times on which it has come up on the wrong; people’s well-being cannot be left simply to the rules of chance.