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reasearch is to study something for a stretch of time(any subject) and establish thesis(or ur findings) on that for which u hv 2 essentially gather lots of information, go places if necessary etc. An investigation on the other hand is a logical and comprehensive establishment/derivation of facts etc. of an event or happening (eg. a murder) to pin pointedly prove how it all happened. Statistics play an imp.role in research while logic and intelligence play a vital role in Investigation.