Hay Festival Special

This week More or Less goes to meet an army of loyal listeners – and a rebellious clique of disloyal ones – at the Hay Festival.

Tim Harford and Ruth Alexander ask which country is the richest. Plus, we pose a multiple choice question about multiple choice questions.

And we’re joined by Professor David Spiegelhalter, who uses statistics to understand the behaviour of one of the world's most dangerous serial killers.