How to Use Expected Value for Life Decisions

What Is Expected Value?

Expected value (EV) is the average outcome you'd get if you made the same decision thousands of times. It's calculated by multiplying each possible outcome by its probability, then summing everything up.

Formula: EV = Sum of (Probability x Payoff) for each outcome

For example, if a job offer has a 70% chance of working out (gaining $30,000/year) and a 30% chance of not working out (losing $5,000 in moving costs), the EV is: (0.70 x $30,000) + (0.30 x -$5,000) = $21,000 - $1,500 = $19,500

That's a positive expected value, which means over time, this type of decision would be profitable.

Why Your Gut Is Wrong

Behavioral economics research by Daniel Kahneman and Amos Tversky shows that humans are terrible at intuitively assessing probabilities. We overweight small probabilities (that's why we buy lottery tickets) and underweight large ones (that's why we skip insurance).

Loss aversion makes us feel losses roughly twice as strongly as equivalent gains. A $100 loss hurts more than a $100 gain feels good. This bias causes us to avoid positive-EV decisions because we're fixated on the downside.

How to Apply EV to Real Decisions

Step 1: List All Possible Outcomes

Don't just think "it works" or "it doesn't." Map out specific scenarios. For a career change, outcomes might include: great success, moderate improvement, lateral move, or setback.

Step 2: Assign Probabilities

Use base rates from real data when possible. Our probability database has 500+ verified stats. For example, the probability of a startup succeeding in its first 5 years is about 50% according to BLS data.

Step 3: Estimate Payoffs

Assign dollar values (or utility scores) to each outcome. Include both financial and non-financial factors. A career that pays less but reduces stress has a quality-of-life payoff.

Step 4: Calculate and Compare

Multiply probability x payoff for each outcome, sum them up, and compare options. The highest EV is your mathematically optimal choice.

When NOT to Use EV

EV works best for repeatable decisions — choices you'll make many times over your life. For truly one-time, catastrophic decisions (like high-risk surgery), you should also consider downside risk and your ability to survive the worst case. That's where our risk assessment and Monte Carlo tools come in.

Start Making Better Decisions

Our decision wizard walks you through this exact process step by step. Input your options, set probabilities using real data from our probability database, and let the math guide you to the smartest choice.