undercount

under- +‎ count

undercount (third-person singular simple present undercounts, present participle undercounting, simple past and past participle undercounted)

1. To count to an insufficient degree; to count one thing disproportionately less than another
   • 2009, January 8, “Brian Stelter”, in Arbitron Settles Lawsuit Alleging Bias in Radio Ratings System‎:

     But minority stations have claimed that they are undercounted in the new system, in part because Arbitron has struggled to include representative numbers of young and minority listeners in its sample.

• overcount

undercount (plural undercounts)

1. An incorrect count that is too low.

• overcount

• untrounced