“Adding details to certain of the alternative future outcomes made them more probable in the minds of our respondents, even though logically the opposite must be the case” Thinking, Fast and Slow, Daniel Kahnemann
“In business, people want an answer quickly. It doesn’t have to be the right answer …” Anonymous
Forecasting, my day job, involves a struggle of conscience. To be credible and thereby successful with clients, it helps to make stories as rich as possible, with evocative snippets to capture the imagination. To be intellectually robust, on the other hand, it is necessary to strip away superfluous detail, to avoid making an unlikely scenario even less likely by burdening it with unsubstantiated paraphernalia. The trouble is, everyone likes a good story.
A similar phenomenon is observable with numbers. The more precise a number, the more accurate it is assumed to be, and the more persuasive it is in consequence. Consider the following statements: a) the Earth’s radius is around 6000 kilometres; and b) the Earth’s radius is 6875.23 kilometres. Which of these statements is easier to believe? In fact, the first statement is more accurate, and correct to the nearest 1000 kilometres. But rounding numbers and using terms such as “about” or “in the region of” suggests to most people in my experience that a job has not been done properly. We think that if a precise answer is given, then careful thought has gone into it, when the opposite might be the case.
Credibility of politicians
In the run-up to the general election, the main parties have been predictably attacking each other, with one of the main insults being that the other party’s figures “don’t add up”. Whilst that is almost inevitably true, the implication that the speaker’s party is any better is not well substantiated.
This particular accusation highlights some of the prejudices we tend to have about precision, “facts”, smooth delivery and credibility. Here are two hypothetical answers to the hypothetical question: how much would it cost to replace all of the diesel passenger cars in Britain with electric vehicles?
Answer A: Our party has undertaken a detailed study into the replacement of all diesel passenger cars by electric vehicles. All of the relevant factors have been fully taken into account and assessed as part of a wide-ranging review. The total cost I can tell you would be £3.26 billion. This is the initial up-front cost. Of course, there would then be savings each year of £426 million per annum associated with cheaper running costs of the electric vehicles, so that within 8 years the scheme would have paid for itself.
Answer B: We have looked into that and produced a draft report. I don’t have the figure to hand, sorry about that. I think it was £100 billion – something like that. Yeah that would be about right – there’s like 10 million diesel vehicles in the country and the cost of replacement and scrappage is something like £10,000 each, I mean per vehicle. I’m talking cost here, not what they would sell for. Of course this cost is changing all the time. I’m not sure about the running cost advantage – guess it depends on the prices of electricity and diesel, engine efficiency, … But I think we estimated it would take at least a decade to pay back.
Two very different answers – so which is more compelling? The first speaker has come prepared and has the numbers at their fingertips. Like that of a good stage actor, the delivery is smooth and assured. There is a clean conclusion (payback within 8 years), which has a reassuring quality. By contrast, the second answer shows the speaker to be unprepared. The delivery is repetitive and ungrammatical; and the conclusion is worryingly vague – an “estimate” that payback would be “at least a decade”.
So if we equate politics with stage-acting, both in the learning of lines and the manner in which they are delivered, there is one winner. But just as an actor does not need to have a deep understanding of reality, there is nothing to suggest the first speaker understands the derivation of the figures that they quote. The second speaker at least appears to be thinking it through; and to be conscious of some of the difficulties that militate against a precise answer to the question that was asked. Maybe if we were to value thoughtfulness above stage delivery, our verdict would be different.