where A is in cm∕s2, c_{1}= 2.308, c_{2}= -1.637, c_{3}= 30 and c_{4}= 0.411 (σ not reported^{1}).
Also derive equation using r_{epi}: c_{1}= 0.982, c_{2}= -0.129, c_{3}= 0 and c_{4}= 0.466 (σ not reported^{2}).

^{1}Reports coefficient of variation of 0.942 which could be the value of σ in terms of natural logarithms.

^{2}Report coefficient of variation of 0.877 which could be the value of σ in terms of natural logarithms.