Bias List

Faulty Deduction


Hard-Easy Effect

The hard–easy effect occurs when, based on a specific level of difficulty of a given task, subjective judgements do not accurately reflect the true difficulty of that task. This manifests as a tendency to overestimate the probability of success in difficult tasks, and to underestimate the probability of success in easy tasks.


Illusion of Validity

Belief that furtherly acquired information generates additional relevant data for predictions, even when it evidently does not.


Insensitivity to Sample Size

The tendency to under-expect variation in small samples.


Jumping to Conclusions

Drawing a quick conclusion without fairly considering relevent (and easily available) evidence.


Less-is-Better Effect

The tendency to prefer a smaller set to a larger set judged separately, but not jointly.


Relativist Fallacy

Rejecting a claim because of a belief that truth is relative to a person or group.


Seersucker Illusion

Over-reliance on expert advice. This has to do with the avoidance of responsibility. People call in "experts" to forecast when typically they have no greater chance of predicting an outcome than the rest of the population. In other words, "for every seer there's a sucker."



Assuming an observation from a small sample size applies to an entire group.


System Justification

Existing social, economic, and political arrangements tend to be preferred, and alternatives disparaged sometimes even at the expense of individual and collective self-interest.