Or, slightly more accurate:
RoR = ((1 - EV / Std.) / (1 + EV/Std.)) ^ (Bankroll / Std.)
And if you want to know how big of a bankroll required for X RoR:
Bankroll = Std. * log(X) / log((1 - EV/Std.)/(1+EV/Std.))
Some others:
N0 = (Std. / EV)^2
Desirability Index (DI) = 1000 * N0^(-0.5)
Where EV and Std. are in $ / round, or Units / round.