This morning’s Observer column.

On Friday 20 July, Obama had 18 million followers, compared with Romney’s 690,000. But over the next few days @MittRomney mysteriously acquired 100,000 new followers.

This immediately attracted the attention of those who track these things. “Is Mitt Romney buying Twitter followers?” asked one prominent observer. Others noted that many of the new “followers” looked dodgy. Five of them shared the same profile photo, for example. Obama supporters gleefully pointed out that buying followers would be absolutely typical of a candidate who was fabulously rich but clueless about cyberspace. Sceptics wondered if the spike was actually orchestrated by Romney’s opponents as a way of discrediting him. Was the spike the product of a Twitter “spambot” – a software robot that creates fake accounts? And so on.

But this was all conjecture and speculation. Everybody was suspicious but nobody knew anything. Then a couple of students at the Oxford Internet Institute asked themselves a question: what’s the probability that Romney’s new followers are genuine? Their account of the research makes fascinating reading…