How should I state 'MS dropout' in my resume when applying for data scientist positions?
First, some advice. I agree with @gnometorule, but I would state it stronger: IMHO and based on limited information you've shared, it would be a mistake to drop out so close to graduation. Even though the current culture within startup ecosystem and, overall, tech industry largely ignores education credentials in favor of "being a hustler", "being a doer", "being street smart", etc., the data science subset of the both areas actually seem to have more respect and pay more attention to people's education. This is quite understandable, considering the relative complexity of data science and, especially, its machine learning and artificial intelligence fields of study and practice.

I would strongly suggest you to consider things in perspective and do your best to successfully finish the program. Not only it will give you some advantages when competing in the job market, but also might be useful to you, should you decide in the future to go for a Ph.D., teach at some educational institution or pursue other opportunities (i.e., scientific research or consulting).

In regard to your specific question - should you decide to ignore my advice - I think that it would be better to formulate in your resume the phrase "MS dropout" not as such or, even, not as


  "University XYZ, MS program, Statistics, Years Range, Incomplete",


but rather as a positive fact / achievement:


  "University XYZ, MS program, Statistics, Years Range, Completed 90% of curriculum".


Having said that, again, I strongly suggest you to consider finishing your Master's program.