Hello and welcome to more or less on the BBC World Service.

We are weekly guide to the numbers all around us in the news and in life, and I'm Tim

Halfard.

Daniel Kahneman is perhaps the best known and most respected psychologist in the world.

He revolutionized our view of biases in decision making alongside his long-time collaborator,

A. M. Tversky, he studied wellbeing, memory, attention and the way we interpret probabilities.

He won a Nobel Memorial Prize and he wrote the blockbuster book of popular social science,

thinking, fast and slow, just over a decade ago.

In that book, he tackled the subject of bias.

The kind of bias that interests Kahneman produces predictable errors in judgment or memory.

The biases that thinking fast and slow is concerned with are so-called cognitive biases.

It's a systematic error.

Yes, this is Daniel Kahneman who kindly sat down with me to talk about his ideas.

Bias is not the only type of error.

Kahneman has written a new book alongside Olivier Sibony and Cass Sunstein.

It's called Noise, a floor in human judgment.

Noise is different from bias.

It's not a predictable error.

Instead, it's a variability in decisions where there shouldn't be variability.

For instance, doctors examining patients but reaching different diagnoses.

The book examines many real life examples of noise.

In the public sphere, there's the role of judges in sentencing.

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