Uber Chief Economist Jonathan Hall published a blog post disputing a Massachusetts Institute of Technology working paper that says Uber and Lyft drivers on average earn $3.37 per hour after adjusting for expenses.

The paper, written by Stanford professor Stephen Zoepf, says that, in addition to making fewer than $4 per hour, one-third of Uber drivers were losing money.

MIT = Mathematically Incompetent Theories (at least as it pertains to ride-sharing). @techreview report differs markedly from other academic studies and @TheRideshareGuy recent survey. Our analysis: https://t.co/S2aAqCuDR0

— dara khosrowshahi (@dkhos) March 3, 2018

Uber CEO Dara Khosrowshahi responded with a tweet, saying, "MIT = Mathematically Incompetent Theories."

In his blog post, Hall cited previous studies that found Uber drivers making higher wages and criticized Zoepf's methodology. He says Uber drivers would be earning closer to $13.04 per hour after expenses.

Zoepf addressed the criticisms on Twitter, finding that drivers earned $8.55 to $10 per hour and roughly 8% of drivers lost money while driving for Uber. He claimed that up to 54% of drivers make less than their state's minimum wage.