To reduce the number of tests, assays such as Y2H typically use pooled screens in which a single protein "bait" is tested for interaction against pools of protein "preys" (phase I) 38 . For pools that test positive, pairwise tests are immediately conducted between the bait and each prey in the pool (phase II-this second phase can also be conducted by sequencing3,5). The benefit of pooling is that large numbers of potential interactions can be sampled at relatively low cost. This comes at the expense of FNR, as the chance a true interaction is missed in the pool is higher than the chance it would be missed by direct pairwise tests38. Through simulation, we found that basic two-phase pooling (Pooling strategy) does indeed achieve a four-to five-fold reduction in coverage cost over pairwise testing (~4 million plates for Pooling compared to ~20 million plates for Basic-serial, Table 1 ). However, assuming the rate of interaction screening of a typical laboratory (e.g., ~2400 plate-matings per person per year), pooled screens would still require approximately 1700 person-years to achieve completion of the Drosophila protein network.