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Statistical methods might be possible. Sampling accounts, using a manual process to find multi-account users and extrapolating the numbers based on the sample.

Yes, but we may need more manual power and the result might not be worth the effort. Let the professional organisations do that if steemit becomes the next Facebook and they want to write about this network's bot problem!

Eventually the reward pool should make it financially worthwhile, but not now.

Yes, Agree.