I don't know how sngwiz defines edge but here are what I think are standard defs.
Four equivalent edge definitions:
• Edge is EV/I, expected value divided by investment or bet amount. If the investment amount is one unit, then edge is equivalent to EV.
• For an even money payout (1 to 1 odds payoff), edge is win probability – lose probability.
• For a non-even money payout, edge is odds payoff * win probability – lose probability
• For a tournament, edge is equal to ROI.
I’ll use roulette to illustrate how edge works. Consider the American system where a roulette wheel has two zeros plus 36 numbers. If you hit a number, the house pays 35 to 1. Without the two zeros, that would be a fair bet but the two zero’s give the house the ‘edge’. How much edge? Let’s use the basic formula, edge being EV/I. Say you bet $10 on your birthday number. If you hit, you win 35 times your bet or 350. If you lose, you lose your $10.