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Musk’s plan to buy Twitter has worried policymakers around the world.
Joe Skipper | Reuters

Elon Musk has said his $44 billion purchase of Twitter will not move ahead until he has more clarity on how many accounts are fake.

Twitter estimated in a filing earlier this month that fewer than 5% of its monetizable daily active users during the first quarter were bots or spam accounts.

But Musk estimates that around 20% of the accounts on Twitter are fake or spam accounts and he’s concerned that the number could be even higher.

“My offer was based on Twitter’s SEC filings being accurate,” Musk tweeted early Tuesday morning. “Yesterday, Twitter’s CEO publicly refused to show proof of <5%. This deal cannot move forward until he does.”

Twitter’s shares slipped 2.22% in pre-market trading on Tuesday. A spokesperson for Twitter did not immediately respond to a CNBC request for comment.

Musk has said his team are conducting their own analysis on the number of fake accounts on the platform, but experts in social media, disinformation and statistical analysis say his suggested approach to further analysis is woefully deficient.

“To find out, my team will do a random sample of 100 followers of @twitter,” Musk tweeted on Friday. “I invite others to repeat the same process and see what they discover.”

He clarified his methodology in subsequent tweets, adding: “Pick any account with a lot of followers,” and “Ignore first 1000 followers, then pick every 10th. I’m open to better ideas.”

Musk also said, without providing evidence, that he picked 100 as the sample size number for his study because that’s the number Twitter uses to calculate the numbers in their earnings reports.

“Any sensible random sampling process is fine. If many people independently get similar results for % of fake/spam/duplicate accounts, that will be telling. I picked 100 as the sample size number, because that is what Twitter uses to calculate <5% fake/spam/duplicate.”

Carl T. Bergstrom, a University of Washington professor who co-wrote a book to help people understand data and avoid being taken in by false claims online, told CNBC that sampling one hundred followers of any single Twitter account should not serve as “due diligence” for making a $44 billion acquisition.

He said that a sample size of 100 is far smaller that the norm for social media researchers studying similar issues and could result in selection bias.

Facebook co-founder Dustin Moskovitz weighed-in on the issue via his own Twitter account, pointing out that Musk’s approach is not actually random, uses too small sample, and leaves room for massive errors.

— Additional reporting by CNBC’s Lora Kolodny.