Step 2: analyze cues
A grid of four cues against three candidate hypotheses, marked supports, refutes or silent, with the surviving column boxed.
Cluster, then explain
Cues are grouped before they are interpreted. A single finding rarely names a condition; a cluster does. Ask of each candidate explanation whether it accounts for every cue in the cluster, not merely the loudest one. An explanation that covers the dramatic finding and ignores two quiet ones has not been tested, only preferred.
Support and refute
Every cue does one of three things to a hypothesis: it supports it, it argues against it, or it is silent. A hypothesis refuted by even one strong cue is out. Candidates lose points by keeping a favorite explanation alive after a cue has already killed it, then hunting for an answer choice that lets them keep it.
Worked cluster
An older adult, second day after hip arthroplasty. Sudden shortness of breath. Sharp chest pain worse on inspiration. Rising heart rate. Breath sounds clear and equal bilaterally.
| Cue | Pulmonary embolism | Pneumonia | Anxiety |
|---|---|---|---|
| Sudden onset of dyspnea | supports | refutes | supports |
| Pleuritic chest pain | supports | supports | silent |
| Rising heart rate | supports | supports | supports |
| Clear bilateral breath sounds | supports | refutes | silent |
Pneumonia is refuted twice: it builds rather than arrives, and clear bilateral sounds argue against consolidation. Anxiety survives no test of its own, because nothing in it explains recent surgery and immobility. Embolism explains the whole cluster.
Margin noteone cue that does not fit outranks three that do.
Watch outA plausible story is not the same as an explained cluster. Anxiety is always plausible. That is exactly why it is offered.
TakeawayThe winning hypothesis explains the whole cluster, and one refuting cue eliminates a candidate outright. → BOOK 02 · P5 · → BOOK 09 · P4