Our findings show that given an initial simulated power estimate for a complex genomic study, power can be approximated by a simple formula, EEE, that can easily be implemented in a matter of minutes in software as simple and widely available as Excel. In addition, computational time involved in simulation studies to calculate power can be prohibitive in certain situations. For example, suppose we have familial data consisting of 800 families with 6,560 individuals and wish to calculate power for association test between SNP and quantitative trait using mixed model and also assume there are 10 different scenarios with respect to effect size. We observed that on a Dell PowerEdge 2650 with the Intel Xeon 2.8 GHz processor and 2 GB of RAM, it took us 2.83 seconds per replicate to simulate and 449 seconds to analyze per replicate. Thus, only generating 2,000 replicates can take about 10.46 days. However, using EEE the computational time in calculating power will be almost negligible. Though some situations exist in which the procedure is not useful, such situations are predictable and in those
