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 weekly guide to the numbers in the news and in life and I'm Tim

Harford and I'm Elizabeth Kassen and this week instead of asking what secrets

we can learn from numbers we'll be asking whether numbers are revealing our

secrets to others.

It's a familiar concern.

Online retailers are tracking us so they can sell things to us.

Brix and mortar retailers have loyalty card schemes.

Our banks and credit card companies know all about us.

And of course the big computer and telecoms companies could potentially track our internet searches,

our phone calls, even our location as we wander around.

But this isn't the first time that large corporations have gathered sensitive data about

their customers. This issue is over a century old.

In the late 19th century a series of American life insurance companies came together

to pool the medical data of their customers. Companies were sharing data on all individuals, even policyholders burdened with any impairment,

where before they had only shared the information about those they were rejecting.

They were so worried that the public would be out... the They called it the MIB.

Sadly not that MIB

As Dan Balk author of how our days became numbered, explains.

The Medical Information Bureau, they are MIB.

And essentially the one and only rule of Fight Club that you don't tell

...