The Gini coefficient, or Gini index, is a common way to gauge income or wealth inequality within a population.

The coefficient gives a single number showing how equal a distribution is. For example, in a population where everyone earns the same amount the Gini coefficient would be 0 — total equality — and in a population where one person earned all of the population's money, the Gini coefficient would be 1 (sometimes expressed as 100%) — maximum inequality. In practice all countries' Gini coefficients are somewhere in between, at around 0.25 to 0.5 after taxes.

Like any simple measure the Gini has its difficulties, like being easily misinterpreted when compared, but is still widely used. The BBC has a short piece on its history and an alternative measure called the Palma ratio.

Of course, we have some high profile zillionaires at the moment. You might like this old sketch of wealth inequality in America.

The Gini coefficient

The front page test is a handy thought experiment for your decision-making ethics: how would you feel if your actions were on the front page of a major newspaper? Would you squirm or would you stand proud?

There are many ways to think about making ethical decisions: sticking to promises, considering the net good and bad consequences, considering what would happen if everyone behaved the same way, and others. The front page test is simple and cuts through much of the noise to how you truly feel about an action.

The front page test

For some obscure reason English speakers will almost always find a flip-flop to be more natural than a flop-flip, or a pitter patter of tiny feet to a patter pitter, or a tick tock to a tock tick. When the vowel changes in a reduplicative term — such as wishy washy or hip hop — it's known as ablaut reduplication and the vowels almost always follow the order I-A-O. If you say them in any other way they almost always sound weird. It's quite fun to think of examples.

I learned this neat thing from Mark Forsyth when learning about the even more surprising English grammar convention about ordering adjectives — he was explaining why we say the Big Bad Wolf (thanks ablaut reduplication) and not the Bad Big Wolf as our other grammar convention would dictate.

Ablaut reduplication