4b.1 Definition of Value and Yield
Betting at the long term you need to follow a long term strategy so as to win a stable income at a long period, maybe months. You have to bet in a regular base and to follow a specific strategy.
There are two parameters to help us to understand long term betting which are:

Value

Yield
Definition of Value:
Value is a mathematical way to understand the value of bookmakers odds. It is calculate from the equation:
Value = (Probability * Demical Odds)  1
Where:
Probability : The calculated probability to win the bet
Betting Odd : Bookmaker’s odd for the specific bet
Let’s make an example. At the game «Brescia vs Perugia» for the Bet «Brescia to win»:
Betpractice Real Odd is 2.24 that means Probability = (1 / 2.24) = 0.4464 or 44.64%
The Betting Odd from the bookmakers (Betfair Exchange) is 2.44
So,
Value = (0.4464 * 2.44)  1 = 0.0892 or 8.92%
Value > 0
If the value is above 0 it is an indicator that the specific betting odd is a valuebet.
That means the calculated probability to win the bet, is higher that the probability derived from bookmakers odd. And that’s true in our case.
The bookmaker’s odd is 2.44 that means Probability = (1 / 2.44) = 0.4098 or 40.98%
So Betpractice Calculated Probability (44.64%) > Bookmakers Probability (40.98%)
In terms of long term betting each time you bet more than a unit, you will get more than a unit back. In this way, you should win money in the long run. If the stakes we place have a value of 1.08, we will get 108€ for every 100€ we bet.
Value < 0
If the value is below 0 it is an indicator that the specific betting odd is a not a valuebet.
That means the calculated probability to win the bet is lower that the probability derived from bookmakers odd.
Value = 0
When value is equal to 0 that means: Calculated Probability = Bookmakers Probability
Definition of Yield:
Yield is a mathematical way to measure betting efficiency compared to total stake.
Yield Formula:
Yield = net [Profit / Loss] / [Total Stake]
Where:
net [Profit / Loss] : net profit or loss
Total stake : Total stake of betting
Let’s make an example,
At table below there is an example of Hunter Platform showing a betting system for "Team 1 to win".
The system includes 44 bets with a stake unit of 1€ for every bet. Total stake was 44.00€.
Betting based on Betfair Exchange returned 46.57€.
So,
net [Profit / Loss] = 46.57 – 44.00 = 2.57€
Total stake = 44.00€
Yield = 2.57 / 44.00 = 0.0584 = 5.84%
Yield means profit 5.84% of your total stake based on Betfair Exchange.