On August 27,2020  the cumulative total of percent negative tests out of the 20,847 valid tests conducted since July 27, 2020 for students at Boston University was 99.84%.  This means that that a mere 0.16% tested positive.  This forms a good basis upon which to track spread  from a near zero base.    Go  to https://www.bu.edu/healthway/community-dashboard/  for  daily  updates.