Figure 2. Frequency of B′ cells in droplet category (3), from Table 2.

The distance above the diagonal line indicates the improvement above starting frequency obtained by screening. Thus, points in the upper left corner yield the greatest improvement from screening. There is a strong effect of q, the average number of B-type (B′ + B) cells per droplet, and a weaker effect of the population frequency of B′ (p). We are only concerned with low values of p, because once p reaches a value of even 0.1, B′ cells will be easily isolated. For low values of q, there is a profound enhancement of B′ cells, so if it is feasible to discriminate category (2) from (3), screening should be highly effective.