When Confidence Exceeds Data: A Practitioner's Framework for Assumption Bias Recognition and Prevention Implementation Guide -Version 2.1

Examines assumption bias—the tendency to fill information gaps with projections rather than evidence—and provides practical methods for reducing decision errors across everyday and high-stakes contexts. Integrating forecasting research and base-rate analysis, it demonstrates how multi-source verification can significantly improve judgment while highlighting how premature certainty can produce consequences ranging from clinical misdiagnosis to catastrophic operational failures.