Anchoring Bias: Why the First Odds You See Shape Your Decisions

Anchoring bias is the cognitive bias where an initial piece of information (the anchor) disproportionately influences your judgment of subsequent information.

In betting, the anchor is often the first odds you see. You browse a bookmaker and see odds of 2.5 for a team to win. You see other bookmakers at 2.3 and 2.7. But that initial 2.5 anchors your judgment. You think 2.5 is "fair," 2.3 is "value," and 2.7 is "bad value."

In reality, fairness should be determined by your model (what the true probability is), not by the first odds you happen to see.

How Anchoring Works

Anchoring has a simple mechanism: your brain uses the anchor as a reference point and doesn't fully adjust away from it.

If I ask you, "Is the boiling point of water higher or lower than 200 degrees Celsius?" you're anchored at 200. When I ask for your estimate, you'll typically estimate closer to 200 than you would have without the anchor.

In betting, if the first odds you see are 2.5, and you think the true probability is 52%, the anchor of 2.5 (implying 40%) pulls your judgment. You might think 2.4 is fair, not realising your true estimate suggests 1.92 is fair.

Where Anchoring Appears in Betting

Comparing across bookmakers. You see Bet365 at 2.3. You check William Hill at 2.5. William Hill feels like better value because it's higher. But if your model says true odds are 2.0, both are bad value. The anchor of 2.3 makes 2.5 feel good.

Looking at opening odds. Opening odds are sometimes sharp (set by professionals) and sometimes dumb (set by algorithms). But whichever they are, they anchor your thinking. If opening odds are 3.0, you think 2.8 is good value when your model suggests 2.2.

Recent price movement. Odds move as money comes in. If odds move from 2.5 to 2.0 (shortening), you might feel like it's worse value now. But if your model says 1.95, both were bad value. The anchor of the previous price distorts your judgment.

Odds from tipsters or alerts. A tipster mentions odds of 3.0 for a pick. When you check the actual odds, they're 2.8. You might think 2.8 is still value because you're anchored at 3.0. But your model should determine value, not the tipster's initial quote.

Why Anchoring Is Dangerous

Anchoring directly damages your expected value:

You calculate that a team has 55% probability to win, implying fair odds of 1.82. An anchor of 2.0 makes 1.95 feel like bad value, so you don't bet. You lose the opportunity for a +EV bet.

Or: you calculate 45% probability, implying fair odds of 1.80. An anchor of 2.0 makes 1.95 feel like great value, so you bet. But it's still -EV. You bet on something that's negative value, losing money in expectation.

Anchoring causes you to make bets you shouldn't make, and avoid bets you should make.

How Professionals Avoid Anchoring

Sharp bettors use a simple protocol: calculate your probability estimate first, before looking at market odds.

1. Research the match
2. Calculate your probability estimate for the outcome
3. Convert to implied odds (1/probability)
4. THEN look at market odds
5. Compare your odds to market odds
6. Only then decide value

By calculating first, they prevent the market odds from anchoring their judgment.

If they looked at market odds first, the market odds would anchor their thinking, and their calculated odds would be pulled toward the market anchor.

How to Implement This

Never check odds before analysis. When you're researching a match, don't look at the odds yet. Do the analysis. Calculate your probability. Convert to odds.

Write down your odds before looking at the market. Make your estimate visible. This prevents the market odds from pulling your estimate toward them.

Only then check the market. Now compare your odds to what the market is offering. The comparison is clean.

Be explicit about what you're comparing. Your odds versus market odds. Not, "this feels like value compared to other books," but "my calculated odds are 1.82 and the market is offering 1.95, so it's value."

Overcoming Anchoring in Already-Placed Bets

If you've already looked at market odds before your analysis, you're anchored. The market odds have influenced your thinking.

To correct this:

1. Force yourself to ignore the market odds
2. Do the analysis fresh
3. Calculate your estimate
4. Write it down
5. Only then compare to market

This takes discipline, but it corrects the anchor's influence.

The Opening Odds Question

Opening odds deserve special mention. Sharp bettors disagree on whether opening odds are reliable anchors.

Some say: opening odds are set by algorithms or sharp money, so they're usually fair. Don't anchor. Calculate independently.

Others say: opening odds are good starting points precisely because they're sharp. You can anchor slightly upward or downward based on new information.

The safest approach: calculate independently without regard to opening odds. If your calculation aligns with opening odds, that's validation. If it differs, investigate why.

Testing Your Susceptibility to Anchoring

Try this exercise:

Pick a match. Calculate your probability estimate without looking at any odds. Convert to implied odds.

Now look at market odds. Are your odds aligned with the market, or were they pulled toward anchors you didn't consciously notice?

Repeat this several times. You'll notice patterns in how much you anchor, and which anchors affect you most.

• Anchoring bias occurs when the first odds you see disproportionately influence your judgment of value, pulling your estimates toward that initial anchor
• Professionals calculate probability estimates independently before looking at market odds to avoid anchoring their judgment
• The safe approach is to calculate your probability estimate, convert it to implied odds, then write it down before comparing to market odds
• Market prices, opening odds, and tipster quotes can all anchor your thinking, causing you to misjudge value
• If you've already looked at market odds, you must force yourself to ignore them and recalculate your estimate independently
• Separating the calculation phase from market observation is essential to clean decision-making and consistent expected value