Frequencies of individuals with 256 possible DS response types in randomized controlled trials. We consider 4 binary variables as follows: exposure E, outcome D, confounder C, and selection variable S (see Figure 1). As shown in Tables 2 and 3, we consider 16 response types for D and 16 response types for S. We let P
and denote the probabilities of E and in the total population, respectively. For the definition of other notations, see Figure 3. Those who are classified into inner dashed rectangles represent individuals selected for analyses (i.e., S = 1) while those who are not classified into the rectangles represent non-selected individuals (i.e., S = 0). See text for details.