Probability and Statistical Biases

Attrition bias

Dropouts from a study change the results.

What Is Attrition bias?

Attrition bias is a thinking trap where dropouts from a study change the results.

How It Tricks You

It can make noisy, incomplete, or poorly framed data feel more meaningful than it is.

Real-World Example

A program looks successful after the unhappy participants drop out.

Seen Online As

• The chart looks convincing before I check the sample.
• One number is being asked to carry the whole argument.
• The data point feels cleaner than the data really is.

What To Ask Instead

Who left, and why?

Related Thinking Traps

• Anchoring bias
• Confirmation bias
• Framing effect
• Loss aversion

Common Situations

• Thinking Traps at Work

Quick FAQ

What is Attrition bias?

Dropouts from a study change the results.

What is an example of Attrition bias?

A program looks successful after the unhappy participants drop out.

How do I spot Attrition bias?

Who left, and why?