Multiple) Correlation, rX with C, between X and covariate(s) C   0.0 0.3 0.4 0.5 0.6 0.7 0.8 0.9 [1-r2X with C]-1 1.0 1.1 1.2 1.4 1.6 2.0 2.8 5.3

Table 5: Sample size multiplier to cover the cost of adjusting for one of more 2 −1confounding variables.The multiplier, is given as a function of the X with C (multiple) correlation, rX with C , between X and the set of confounding variables C. It is rounded up, and given to two significant digits.