"I had a nice phone conversation with our very own Deer, Elk and Moose Management Specialist, Chad Stewart. He has had the benefit of working both in Michigan as well as Indiana, where they have mandatory check, and no survey system. He was kind enough to help me break down the benefits and challenges of the different ways of making harvest estimates - yes they both estimates either way. Neither state has a concrete, definitive number of how many deer were harvested in a given year."

http://www.mucc.org/why_plus_minus_is_good_enough_for_deer_management

I would think that by having mandatory check in, Indiana would be more accurate, not 100% of course, but as stated, at least showing the minimum of deer killed....