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Better-Than-Average Effect: Most Feel Above Median
The better-than-average effect is the tendency for most people to rate their own skill above the median, even though by definition only half of any group can be. In investing, that quiet inflation of self-assessment is a root of overconfidence.
Key Takeaways
- The better-than-average effect is rating your own ability above the median when only half a group can be.
- Surveys repeatedly find large majorities calling themselves above-average drivers, an impossibility.
- Ambiguity about what counts as skill drives the effect, since vague yardsticks favor a flattering self-view.
- Clear, specific performance definitions and benchmark comparisons shrink the bias for investors.
Key Takeaways
- The better-than-average effect is rating your own ability above the median when only half a group can be.
- Surveys repeatedly find large majorities calling themselves above-average drivers, an impossibility.
- Ambiguity about what counts as skill drives the effect, since vague yardsticks favor a flattering self-view.
- Clear, specific performance definitions and benchmark comparisons shrink the bias for investors.
What It Is
The better-than-average effect, also called overplacement, is the pattern where a majority of people place themselves above the midpoint of a group on some desirable trait or skill. It is a comparison error: not about how good you are in absolute terms, but about where you rank relative to others.
The arithmetic makes the problem clear. In any group, only half can be above the median. When 70 or 80% claim to be above it, most of those people are wrong by simple logic, regardless of how the trait is measured.
The Intuition
People want to see themselves favorably, and a vague comparison gives them room to do it. If skill is fuzzy, you can quietly define it around your own strengths and conclude you are above average.
Driving is the classic case. Repeated surveys find large majorities rating themselves as better than the average driver, and one well-known study found 93% of US drivers placing themselves above average. The same instinct shows up in investing, where most participants believe they have better judgment, better information, or better discipline than the typical investor they are competing against.
How It Works
A major driver is ambiguity. Research summarized by Don Moore shows that fuzzy, hard-to-measure abilities produce strong better-than-average effects, because everyone interprets the trait in a self-flattering way. Clarify exactly what the skill means and the effect shrinks.
A second mechanism involves how people read the word average. One line of research finds that for abilities people consider easy, they construe average as below the true median, around the 40th percentile, which makes clearing the bar feel automatic and inflates above-average claims. The CFA Institute ties this overplacement directly to overconfident investors who believe their knowledge and ability beat the market.
ambiguous skill -> self-flattering definition -> "above average" feels true
clear, measured skill -> harder to spin -> effect shrinks
The bias is strongest precisely where it is hardest to check, which is most of investing.
Worked Example
Survey a room of 100 active investors and ask each whether their stock-picking skill is above or below the median of the group. Suppose 75 say above and 25 say below.
By definition, only 50 can truly be above the median. At least 25 of the above-average claimants are wrong. They are not lying. Each has constructed a private definition of skill, weighting the things they do well, ignoring the things they do not, and reading average as a low bar.
Now connect it to behavior. An investor who believes they rank in the top quarter will trade more, concentrate more, and pay less attention to low-cost index alternatives, because those are for average investors and they have placed themselves above that. The misplaced ranking, not any measured edge, is what licenses the riskier behavior. A simple fix is to define skill concretely, for example, after-cost return versus a broad index over five years, and compare against that.
Common Mistakes
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Judging skill on a vague yardstick. The fuzzier the measure, the easier it is to rate yourself high. Pin skill to a specific, checkable number.
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Reading average as a low bar. People often treat average as below the real median. Remember that beating the typical investor means beating roughly half of everyone, including professionals.
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Skipping the benchmark. Believing you are above average is cheap until you compare your after-cost returns to an index. Run the comparison before you conclude you have an edge.
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Letting rank license risk. Feeling top-quartile invites concentration and heavy trading. Size and diversify by rule, not by self-assessment.
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Confusing effort or interest with skill. Caring a lot about investing does not place you above the median at it. Engagement and ability are different things.
Frequently Asked Questions
What is the better-than-average effect in simple terms? The better-than-average effect is when most people rate themselves as above the midpoint of a group on a skill, even though only half can actually be above it. It is a flaw in how we compare ourselves to others.
How does the better-than-average effect affect investment decisions? Investors who believe they rank above the typical investor trade more, concentrate more, and dismiss low-cost index funds as being for average people. The misplaced ranking licenses risk that measured skill does not support.
What is a real-world example of the better-than-average effect? Surveys repeatedly find large majorities of drivers, in one study 93% of US drivers, rating themselves above average, which is mathematically impossible for that many people.
How can investors counter the better-than-average effect? Define skill with a specific, checkable measure such as after-cost return versus a broad index over several years, then compare honestly. Clear definitions shrink the bias more than willpower does.
How is the better-than-average effect different from overconfidence calibration? The better-than-average effect is overplacement, ranking yourself above others. Calibration is about overprecision, being too sure your own estimates are accurate. One compares you to others, the other to reality.
Sources
- Moore, D. A. "How to Remedy Better-than-Average Effects." Behavioral Scientist. https://behavioralscientist.org/how-to-remedy-better-than-average-effects/
- Frontiers in Psychology. "The Better-Than-Average Effect Is Observed Because 'Average' Is Often Construed as Below-Median Ability." https://www.frontiersin.org/journals/psychology/articles/10.3389/fpsyg.2017.00898/full
- PMC. "I Am a Better Driver Than You Think: Examining Self-Enhancement for Driving Ability." https://pmc.ncbi.nlm.nih.gov/articles/PMC3835346/
- CFA Institute. "The Behavioral Biases of Individuals." https://www.cfainstitute.org/insights/professional-learning/refresher-readings/2026/the-behavioral-biases-of-individuals
Disclaimer
This article is educational content only and is not financial advice. Nothing here is a recommendation to buy, sell, or hold any security. Consult a licensed advisor before making investment decisions.