The complete rule
Choose the one clue that does not satisfy the most precise relationship shared by the other three. A complete solution includes both parts: the outsider and the rule connecting the remaining clues. The intended explanation is revealed after the choice so the result is not based on taste alone.
Choose the strongest connection
Describe all three. A good answer explains the shared property, not only the outsider.
Avoid vague links. Prefer one precise category over several loose associations.
Check alternatives. If two answers seem possible, look for the more exact rule.
A worked example
Given MERCURY, VENUS, EARTH and MOON, “MOON” is the clean outsider because the other three are planets. Saying “MOON is smaller” is weaker: it does not state one exact property shared by all three alternatives, and relative size is not the clean category the clues support.
Use a claim-and-check method
Start with a complete claim: “These three are all types of …” or “These three can all be preceded by …”. Test the wording against every selected clue. If one item needs an exception or a second meaning that the others do not, the rule may be too loose.
Next, test the proposed outsider against the same rule. The strongest answer explains why it fails without relying on personal taste, size or another vague difference. A puzzle can contain tempting secondary associations, so prefer the rule that accounts for all four clues most cleanly.
Accessibility and ambiguity
Each clue is selectable as a labelled text control, and the revealed result explains the relationship in words rather than colour alone. If you can justify a different precise rule, compare it with the published explanation. Use the correction route when two answers appear equally defensible; the puzzle standard explains how ambiguity is reviewed.
Learn from the revealed explanation
After revealing the answer, compare its wording with your own. If your outsider was correct for a different defensible reason, record both rules and decide which one is more precise. If it was wrong, identify the clue that should have challenged your first idea.
Try today’s Four Links next, browse the recent puzzle archive, or use the weekly printable pack for an offline connection challenge.