Hello and welcome to more or less on the BBC World Service, with a program that harvests

grains of truth from the endless prayers of dodgy data, and I'm Tim Harford.

As the Russian invasion of Ukraine continues, the effect ripple around the rest of the world.

One concern involves the wheat harvest, with papers such as The New York Times writing,

Ukraine invasion threatens global wheat supply, Russia and Ukraine together supply more than

one quarter of the world's wheat.

That's a lot of wheat.

At least it sounds like a lot.

Does this mean we'll have a shortfall of 25 percent?

To find out more, I spoke to Dr Hannah Richey, head of research at R-World in Data and

a senior researcher at the University of Oxford.

The statistic is true that Ukraine and Russia combined produce 25 percent, so around

a quarter of the world's wheat exports.

What that doesn't mean is that if they produced nothing this year, that we would have a

shortfall of 25 percent.

Hmm, one of the classic blunders.

It's true that together, Ukraine and Russia produce around one quarter of the world's

wheat exports, but they do not, as the New York Times states, supply more than one quarter

of the world's wheat.

So the headline is incorrect.

Let us elucidate.

What you're saying is the world doesn't have to fill in that 25 percent gap.

...