Comparison
Base Rate Neglect vs Availability Heuristic
Main difference in one sentence
Base Rate Neglect ignores the big background numbers, while Availability Heuristic overweights whatever example comes to mind most easily.
Number Mistakes
Statistical & Probability Errors
Base Rate Neglect is a probability mistake. The person skips the broader odds and gives too much weight to one specific clue, result, or case.
Fast Rules of Thumb
Heuristics
Availability Heuristic is a mental shortcut. The person treats vivid, recent, or memorable examples as if they reveal how common something really is.
Example where people confuse them
After hearing one dramatic illness story, someone thinks a rare disease is likely. If the main problem is that the memorable story feels common, that is Availability Heuristic. If they also ignore the fact that the disease is extremely rare in the broader population, that is Base Rate Neglect.
Quick memory trick
Availability asks, “What comes to mind fast?” Base rate asks, “What are the background odds?”