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This is the short edition of More or Less,

first broadcast on the BBC World Service.

Hello and welcome to More or Less on the BBC World Service.

We're your guide to the numbers that surround us in the news and in life,

and I'm Tim Harford.

Are you nervous about making big decisions?

Well, don't be.

Because I have a large, yet portable bag full of numbers to help you out.

They come from a new book, Naked Statistics,

which aims to show how statistics can be used to answer many of life's questions.

I called up the author, Charles Wheeler,

and asked him whether he could serve as my statistical guide through parenthood.

So let's start by examining one of those pieces of advice

commonly given to expectant mothers.

Try to avoid caffeine.

What does the evidence say?

There's a new book by Emily Oster called Expecting Better

that summarizes a lot of the data around healthy pregnancies,

and she casts serious doubt on that particular piece of advice.

...