The number, on a scale of 1-100 which is derived from the ratio of idiocy within a given population, compared to the population's ability to perform a given function.

For example, a large business. Every big operation carries a few idiots, but the organization is able to work around them, and (hopefully) absorb the big mistakes that result from idiots.

Same with countries. I suppose. A very smart country would be expected to be more successful, better managed etc.

At a micro scale, consider a car. Population, 1 driver, a few passengers. In that case the idiot absorption capacity would be zero. Only one idiot behind the wheel needed for an accident.

So of course we need to agree on the definition of "idiot" and "idiocy".

I propose accepting the wikipedia definition:

"An idiot, dolt, or dullard is a mentally deficient person, or someone who acts in a self-defeating or significantly counterproductive way. Archaically the word mome has also been used. The similar terms moron, imbecile, and cretin have all gained specialized meanings in modern times. An idiot is said to be idiotic, and to suffer from idiocy. A dunce is an idiot who is specifically incapable of learning. An idiot differs from a fool (who is unwise) and an ignoramus (who is uneducated/an ignorant), neither of which refers to someone with low intelligence."