A single vivid case outweighs data when decision stakes are high.

Evidence

Street-level bureaucrats are conspicuously prone to scan their environment for empirical validation of their views. Their conceptions of clients tend to be consistent with perspectives that exonerate them from responsibility for clients’ fate. They are particularly inclined to believe that experience provides the basis for knowledge in assessing the client world. While validity by illustration is logically indefensible it is a significant social fact that influences street-level behavior. We may hypothesize that validity by illustration (“I know it’s true because 1 once had a client who … ”) will prevail in proportion to the worker’s need to cope with the uncertainties of decision making and the potential consequences of those decisions. The policeman who draws a gun hastHy because another officer was recently slain with a knife when he failed to draw his gun has a powerful argument with which to defend himself when questioned for abridging department policy. — Michael Lipsky, Street-Level Bureaucracy, 842

Categorization

• DEFINE: Introduces ‘validity by illustration’ — the anecdotal-evidence fallacy as an operative professional norm, not mere sloppiness.
• XREF: Echoes heuristics-and-biases research (availability and representativeness) but relocates the cause in institutional pressure rather than cognition alone. — connects to: Big data and AI outperform human judgment in high-stakes decisions. — Joseph Avery, Jim Sidanius, Joel Cooper, Gregory Davis, Amanda N., Bias in the Law: A Definitive Look at…, 1171; Decision makers favor readily available information over information relevant to the question — John T. Jost and Jim Sidanius, Political Psychology, 2618
• QUESTION: If anecdotal validity scales with uncertainty and consequence, can it be measured across agencies to predict where stereotypes harden fastest?

Broader Connections

• Big data and AI outperform human judgment in high-stakes decisions. #contradicts (0.90) — Joseph Avery, Jim Sidanius, Joel Cooper, Gregory Davis, Amanda N., Bias in the Law, 1171
• Decision makers favor readily available information over information relevant to the question #expands (0.85) — John T. Jost and Jim Sidanius, Political Psychology, 2618