With four options and a quarter-mark penalty, a blind guess has an expected value of zero. Eliminating one option makes it positive; guessing on questions where you have eliminated nothing but feel confident is where candidates lose marks without realising.
The arithmetic assumes your elimination is genuine. Feeling confident is not the same as having eliminated an option, and the difference is what the calculator makes visible.
Every candidate has heard that you should guess if you can eliminate two options. Almost none have worked out what their own guessing is actually costing them across a full paper, which is a number they can measure.
Four options, +4 for correct, −1 for wrong.
| Situation | Chance correct | Expected value | Guess? |
|---|---|---|---|
| No elimination | 25% | (0.25×4) − (0.75×1) = +0.25 | Marginal |
| One eliminated | 33% | (0.33×4) − (0.67×1) = +0.65 | Yes |
| Two eliminated | 50% | (0.5×4) − (0.5×1) = +1.50 | Clearly |
| Feels right, nothing eliminated | Often below 25% | Frequently negative | No |
When a distractor is well written, the option that feels right to a candidate who has misunderstood the concept is the one designed to attract exactly that misunderstanding. In those cases the candidate performs worse than chance.
Measuring your own accuracy on questions you guessed — which the calculator does from your attempt history — often shows it sitting below the random baseline. That is worth knowing before an exam rather than after.
Phrased the way they arrive, answered so each one stands on its own.
On a four-option paper with a quarter-mark penalty, yes — expected value turns clearly positive. The important qualifier is that the elimination has to be genuine rather than a feeling.
No. Blind guessing is roughly break-even, and guessing where you feel confident without having eliminated anything is often worse than random, because good distractors attract specific misunderstandings.
The calculator computes it from questions you marked as guesses in your attempt history. Most candidates find it lower than they expected.
Checked by the Product desk on 1 September 2026. Corrections go in the page, dated, rather than quietly.
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