The objective for any sports trader is to beat the closing line of the sharpest odds bookmakers. Successful sports traders do not win every bet they place, but they bet knowing that they have a positive expected value (+EV). Which means placing bets that make more profit than their losing bets. With a small sample of bets anything can happen, however, over a large volume of trades and subject to a true edge over the closing line, the bettors bankroll will certainly increase. The standard deviation or variance in the bankroll value will even out as described in our section "Certainty of edge bet profits". Sharp closing lines (odds) offered by sharp bookmakers’ compared to softer (greater odds) lines provide a benchmark to calculate expected value (EV). Meaning that If a sports bettor bets at higher odds than the closing line of the sharpest bookmakers a +EV outcome and profits are assured over time. Inversely if a bettor bets a lower odds than the closing line of the sharpest bookmakers a -EV outcome and losses are assured over time.