Fig. 2From: Diarrhea prevalence in a randomized, controlled prospective trial of point-of-use water filters in homes and schools in the Dominican RepublicDepiction of the assignment of schools and households to treatment groups. Depending upon whether the school in the village accepted or declined a filter, villages were initially assigned to either four or two treatment groups, respectively. In order to ensure that all households and schools that accepted a filter ultimately received one, secondary randomization of control group households was performed as depicted in the figureBack to article page