It has become the political buzzword of the decade: populism is said to explain political movements from Brexit to the rise of Donald Trump. But how has it taken hold – and can it be quantified? The Guardian’s Paul Lewis investigates. Plus: Sam Delaney on the problem with men and mental health

A team of researchers around the world has been working with the Guardian to measure exactly how global politics is changing – and becoming more populist. From Donald Trump in the US to Recep Tayyip Erdoğan in Turkey, from Narendra Modi in India to Theresa May in the UK, the researchers analysed hundreds of speeches, and what they found surprised them.

The Guardian’s Paul Lewis tells Anushka Asthana about the two-decade surge in populist rhetoric that has upended the global political landscape.

Also: writer and broadcaster Sam Delaney on the problem with men and mental health.