Why an honest online test won't give you an IQ score
What sits behind the number
An IQ is not a physical quantity like height but a comparative value: the average of a norm sample is set to 100, the spread to 15 points. “IQ 115” therefore means only: better than about 84 out of 100 people in that sample. The number is only ever as good as the sample behind it — and the conditions under which testing happened.
The measurement error hardly anyone mentions
Even the best professional instruments — over an hour long, supervised, scored by trained staff — measure with an uncertainty band in the order of about ±5 points around the obtained value. Day form, motivation, sleep and practice effects come on top. A single pin-point number is therefore always a simplification; serious assessments state confidence intervals for exactly this reason.
An online test has additional handicaps: no supervision, unknown devices and surroundings, shorter duration — and usually a self-selected comparison group instead of a true norm sample. Each of these limitations widens the uncertainty band. There is nothing shameful about that. It only becomes dishonest when the end screen still says “Your IQ: 132” — precise to the point, gladly with a certificate for a surcharge.
What is honestly measurable online
What measures well is relative performance in reasoning: continuing patterns, completing series, spotting the odd one out. Such puzzles work without language, so they do not hinge on how well someone speaks the test's language. The result can be reported honestly as a range: “your performance sits roughly here, plus or minus this much.” With every additional puzzle the range narrows — but it never disappears.
How our thinking test implements this
The thinking test consists of 44 non-verbal puzzles in four rounds; you may stop after any round. At the end you get an honest performance range with its measurement error stated — and if the range is too wide for a placement, we say exactly that instead of guessing. The test is currently in its calibration phase, which is also stated openly. The result is free, no account.
When a proper IQ test makes sense
When a decision hangs on the number — school placement, special-needs assessment, clinical questions — the measurement belongs in professional hands: a full-length instrument, supervised, with a true norm sample and a report that states confidence intervals. An online test can offer orientation and the joy of puzzling — it does not replace an assessment, ours included.