Noise in Professional Judgment and Why Clinical Reasoning Matters

Mark defines clinical reasoning as a collaborative process of inquiry and analysis aimed at understanding the patient, their context and their problems, combining fast first impressions with slower analysis. Drawing on Daniel Kahneman and colleagues' book Noise, he shows wide variation in sentencing, asylum decisions, parole, opioid prescribing and medical diagnosis, including only 64% agreement in diagnosing melanoma. Physiotherapy shows the same pattern. Agreement ranged from 39 to 72% for pathoanatomical judgments of low back pain, 93 to 100% for credentialed McKenzie therapists, 75 to 83% for movement system impairment judgments and 73 to 97% for cognitive functional therapy. Structural diagnosis is harder in the spine, hip and shoulder, yet one study identified the symptomatic cervical segment in 91 to 98% of cases. Safety judgments vary too: final year students across 15 European countries recognized potential red flags in only 53% of cases, and many physiotherapists underestimated high probability DVT cases. Noise in psychosocial, causal, procedural and prognostic judgments has not been studied.