In their publication Impact of Length of Rank Order List on Main Residency Match Outcome:2002-2015, the NRMP reports that matched applicants consistently have longer rank order lists than unmatched applicants.
What that means to those approaching the residency application process is that candidates should throw a wide net in choosing programs at which to apply. Of course, there is a cost to this strategy, and that expense needs to be balanced. However, if you can afford it, starting out with more options usually will provide more opportunities to interview and thus, the ability to create a longer rank order list.
