Sorry, the first 36.8% of candidates, you’re out

It’s great that life can be expressed in hard and fast numbers, isn’t it? Whatever would we do if the world were a damn sight more difficult to fathom?

But recently we learnt that the best number of people to have in a meeting is seven. Specifically, that for contestant number 8 and each person thereafter, the group’s effectiveness is reduced by something like 10%. I am as wary of bandying numbers about as you are, so let me just point you at that story: Sorry, Snow White, You’re Out

Now there’s more. Specifically this: don’t hire anybody from the first 36.8% of candidates you interview. Seriously.

America’s National Public Radio (via Lifehacker) describes what’s reportedly known as either the Marriage Problem or the Secretary Problem. It’s a thing. It’s been a thing from sometime in the Stone Age where these two issues were considered to boil down to the same thing: how a man (always a man) should choose the perfect woman (always a girl) for him and nuts to whether she’s got her own sliderule equation about him.

NPR’s story is based on a tale told by author Alex Bellos in The Grapes of Math (UK edition, US edition) – his new and so-gorgeously-titled book that I’m going to buy it right after we’re done.

Alex writes: “Imagine that you are interviewing 20 people to be your secretary [or your spouse or your garage mechanic] with the rule that you must decide at the end of each interview whether or not to give that applicant the job.” If you offer the job to somebody, game’s up. You can’t go on and meet the others. “If you haven’t chosen anyone by the time you see the last candidate, you must offer the job to her,” Alex writes (not assuming that all secretaries are female — he’s just adapting the attitudes of the early ’60s).

So remember: At the end of each interview, you either make an offer or you move on.

If you don’t make an offer, no going back. Once you make an offer, the game stops.

According to Martin Gardner, who in 1960 described the formula (partly worked out earlier by others), the best way to proceed is to interview (or date) the first 36.8 percent of the candidates. Don’t hire (or marry) any of them, but as soon as you meet a candidate who’s better than the best of that first group — that’s the one you choose! Yes, the Very Best Candidate might show up in that first 36.8 percent — in which case you’ll be stuck with second best, but still, if you like favorable odds, this is the best way to go.

How To Marry The Right Girl: A Mathematical Solution – Robert Krulwich, NPR (15 May 2014)

It’s easy to mock the way men think there’s logic to dating, so let’s.

But the 36.8% figure has some solid reasoning and also an interesting mathematical history. So do read NPR’s article for more and then do buy Bellos’s book (UK edition, US edition).

Creativity isn’t a separate deal

Education gets so focused on exams that it becomes siloed into specifically what gets examined and when. There is less learning for the sake of learning and there is an inherent assumption that subjects are different to each other. There is then an assumption the creativity is something that gets labelled as a subject to be handled on its own.

So many of our gut thoughts about creativity are not true. You can be creative in math and science. Creativity can be integrated into the classroom experience. Creativity is not simply another word for “arts and crafts.”

The Dangers of Creativity Advocates – The Creativity Post

The Creativity Post’s full article is about how championing creativity is a good and great thing yet it can damage us too.

The statistics behind BOGOF

I’ve noticed that whoever walks in to a supermarket at the same time as me is who will walk out at the same time too. We are driven around stores like machines, guided to what we want and where they want us to buy it, then kicked out as quickly and profitably as possible. I’m fascinated by how these stores work and so this article held me up this morning.

Once Dangler has set up his basic pricing rules, he’s ready to start testing out potential discounts and special offers to try and improve sales. He goes for an aggressive price cut on the own-brand natural yogurt, cutting the profit margin to a few pennies, and the volume of predicted sales balloons as a result. It turns out that people are really price-sensitive when buying cold desserts. Alas, a large proportion of the gains is offset by a drop in branded sales, meaning the idea would probably result in worsening relationships with suppliers in exchange for a modest increase in profits. We keep searching for the optimal solution, with every small change having an immediate trickle-down effect on related products. It’s like a chaos theory testing suite, with each price being a flap of a butterfly’s wings. The only thing missing is a button to make the system automatically optimize everything, you still need humans to input scenarios.

Along the way, I discover phenomena like asymmetric cross-price elasticity — an eight-pack’s price affects sales of four-packs more strongly than vice versa — and the fact that a “buy one, get one free” offer is more cost efficient than a straight 50 percent price cut (that’s because some people will still take just one).

You Priced This Milkshake – The Verge

Read the whole piece to find out who this Dangler is and how while this is an article about American supermarkets, it is featuring software owned by Tesco here in the UK.