Who do you trust? How data is helping us decide

Faced with a choice of babysitters, which do you rely on: your instinct - or the algorithm that tells you to book the one in the green top?

My first lesson in the dangers of trusting strangers came in 1983, not long after I turned five, when an unfamiliar woman entered our house. Doris, from Glasgow, was in her late 20s and starting as our nanny. My mum had found her through a posh magazine called The Lady.

Doris arrived wearing a Salvation Army uniform, complete with bonnet. "I remember her thick Scottish accent," Mum recalls. "She told me she'd worked with kids of a similar age and was a member of the Salvation Army because she enjoyed helping people. But, honestly, she had me at hello."