Cognitive biases & decision-making · law 067
Dunning–Kruger Effect
By Shivam Bhandari · Reviewed 31 October 2026 · How we write
what it means
People with low skill in an area tend to overestimate their ability, while experts often underestimate theirs.
How Dunning–Kruger Effect works
When you know little about a field, you also lack the knowledge to see your own mistakes. Confidence runs ahead of competence. As people learn more, they see how much they don't know and confidence often dips.
For business owners, it explains overconfident first-time decisions in unfamiliar areas — tax, law, hiring, technology — and why outside expertise and feedback are so valuable.
where it comes from
Psychologists David Dunning and Justin Kruger at Cornell University published the study in 1999, testing people on logic, grammar, and humour. Some later researchers argue part of the pattern is a statistical artefact, but the practical lesson holds.
Dunning–Kruger Effect examples in business
New founders
A first-time founder is sure they can build a sales team without help, then loses a year to bad hires.
DIY finance
An owner handles GST filings alone and misses rules an accountant would have caught.
Hiring
Confident candidates can outshine more capable but modest ones in interviews.
How to apply it
- 1In any new area, assume you know less than you think.
- 2Ask an expert to review your plan before you commit.
- 3Use structured tests, not confidence, to judge candidates.
- 4Seek honest feedback regularly from people who know more.
common misreading
It is not a label to throw at others. Everyone is a beginner in most fields, including you.
ask yourself
In which part of your business are you most confident — and least experienced?
put it into practice
Frequently asked questions
What is Dunning–Kruger Effect?
People with low skill in an area tend to overestimate their ability, while experts often underestimate theirs. When you know little about a field, you also lack the knowledge to see your own mistakes. Confidence runs ahead of competence. As people learn more, they see how much they don't know and confidence often dips.
Who came up with Dunning–Kruger Effect?
Psychologists David Dunning and Justin Kruger at Cornell University published the study in 1999, testing people on logic, grammar, and humour. Some later researchers argue part of the pattern is a statistical artefact, but the practical lesson holds.
How do you apply Dunning–Kruger Effect in business?
1. In any new area, assume you know less than you think. 2. Ask an expert to review your plan before you commit. 3. Use structured tests, not confidence, to judge candidates. 4. Seek honest feedback regularly from people who know more.
What is a common misunderstanding of Dunning–Kruger Effect?
It is not a label to throw at others. Everyone is a beginner in most fields, including you.