If you truly want to be a specialist in big data analytics I think a statistics degree is more relevant.
9 out of 10 statisticians might agree. They'd be wrong, though. Few higher level degrees are relevant to non research work directly. Techniques change all the time, that's not why he should get another degree. He should get another degree to make him more easily hireable/promotable. Get an MBA, it's easy and all the kids are doing it.
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