Data · 2026-03-02

Mistype is the norm, not the exception

Function-level testing consistently disagrees with dichotomy testing for a substantial minority of people. The disagreement is not random: it clusters around specific pairs — INTJ/INTP, INFJ/INFP, ENTP/ENFP — because those pairs differ mainly in which function leads, and a comparative questionnaire cannot see that.

Key points

• Disagreement concentrates in pairs that differ in stack order rather than in letter content.
• The four letters a dichotomy test reports are the least informative output of a function test.
• Publishing your own disagreement rate is more useful to the community than claiming accuracy.

More research

• The share of people in your type is a range, not a number
• Why four-letter results change between sittings
• What a flat function profile actually means

Keep reading

• Our methodology and findings
• How this compares to other approaches
• All sixteen type stacks
• How common is each type
• The eight cognitive functions
• About this project
• Privacy and data handling
• Disclaimer and trademark notice