Module 4 · Evidence-Based Diagnosis
4.8 Diagnostic Error
11 min read
Everything in this module assumes the surveyor is trying to get it right. Most are. The errors that matter in this field are not made by people cutting corners — they are made by experienced practitioners with good instruments, working carefully, arriving confidently at the wrong answer. That happens through a small number of well-documented mechanisms, and knowing them is the difference between a career of accumulating expertise and a career of accumulating the same mistake.
Learning objectives
By the end of this lesson you will be able to:
- Name the cognitive mechanisms that produce diagnostic error in survey work.
- Recognise the situational conditions that make each more likely.
- Apply specific countermeasures rather than resolving to be careful.
- Recognise how commercial structure shapes diagnosis without anyone intending it.
Key terms
- Anchoring
- Over-weighting the first piece of information received, so subsequent evidence is interpreted relative to it rather than on its own terms.
- Confirmation bias
- Preferentially seeking and crediting evidence that supports the current hypothesis, and discounting what does not.
- Availability
- Judging a mechanism likely because instances of it come to mind easily — usually because you saw one recently.
- Premature closure
- Stopping the search at the first sufficient explanation, before establishing it is the only one or the main one.
Read the rest of Evidence-Based Diagnosis
Module 1 is open to everyone. The remaining six modules — building science, each damp mechanism in depth, meters and thermal imaging, the full inspection method, and report writing — are free too. We just ask for an email so you can pick up where you left off, and so we can send your certificate when you finish.