Glossary
Rasch model
Definition
The Rasch model is a scoring method from item response theory. It says the chance of answering an item correctly depends on just two things: your ability and the item difficulty, both on the same scale. When ability equals difficulty, the chance is exactly one in two.
Want your own number? The test is 25 visual puzzles, about 12 minutes, no sign-up.
How it works
Each item has a difficulty, written b. Each person has an ability, written theta. Both sit on a logit scale centered near 0. If your theta is above an item's b, you are more likely than not to answer it correctly; if below, less likely. The model finds the theta that best explains the full pattern of your right and wrong answers, along with a standard error.
An example
Two people each answer 18 puzzles correctly. One got most of the hard matrix items right and missed some easy ones; the other did the reverse. A plain count treats them the same. A Rasch model weighs each answer against the difficulty of the item, so the estimates can differ.
How IQ Octopus uses it
The test has 25 items in five sections. Difficulty values are set by design for each puzzle template and refined from accumulated response data over time. The ability estimate is turned into an estimated IQ on the standard scale, and the standard error becomes the confidence range on the report.
Common confusions
A Rasch model does not make a short test as precise as a long clinical one; it makes the most of the answers it has. See item response theory, item difficulty and how the test works.
Try one · Abstract Reasoning
Which tile completes the grid?
Tap the option you think is right, or show the answer.
Show the answer
The missing tile has a large solid triangle (option 3).
How to solve it
- Start with the first column and name what changes from tile to tile.
- Every row and every column contains each shape (hexagon, triangle and square) exactly once.
- Every row and every column contains each fill (solid, hatched and outline) exactly once.
- The size (large) stays the same in every tile.
- Check the rules on the second column, then apply them to the third.
- So the missing tile has a large solid triangle.
That was 1 puzzle. The full test has 25.