There’s a wonky number at the core of Elon Musk’s case against Twitter

Kristen Radtke / The Verge; Getty Images

Listening to the lawyers representing Elon Musk and Twitter argue over which documents need to be provided as part of legal discovery today, I began to wonder if it is possible to measure anything at all.

The arguments centered on a wonky count of user numbers: mDAUs, or “monetizable daily active users.” It’s a nonstandard measure — most social media companies use daily or monthly active users — that focuses on which users can see ads. But Twitter is a nonstandard social media company!

“We are allowed to question their process.”

Twitter is suing Musk for abandoning a deal to buy the company for $44 billion. Part of Musk’s argument is that he was misled about the amount of spam and bots on the platform and that, therefore, the deal can’t...