Noise: A Flaw in Human Judgment

Wherever there is judgement, there must be noise.

Judgments are human measurements. We predict if a tumor is benign or not, we decide how long the appropriate prison sentence for a certain crime should be, we choose who the best hire for an open position is. And we want these processes to be consistent and fair. We want the sense of security of receiving the same prognosis from different doctors, we want a crime to receive a similar sentence even if judged by different judges, we want the confirmation that the best candidate always receives the job.

But, obviously, this is not the case. Human judgements are clouded by biases and noise. Biases are easier to pick out, easier to attack, easier to take as the scapegoat. But Kahneman & Co show that noise is equally to blame for large variabilities in human judgement.


System noise ... noise observed in organizations that employ interchangeable professionals to make decisions
Level noise ... when some judges are harsher and others are milder, due to the ambiguity of the judgement scale.
Pattern noise ... variability due to each judge's individual opinions and experiences.
Occasion noise ... if the same person judges different based on time of day, mood, or external influence.

Important to note that this book deals with noise in systems where there should be no noise. There are many other domains of judgements where diversity in opinions is welcome.

Interesting topic, going too much into detail for me though. I would have preferred for it to be a bit more concise. But it's probably eye-opening for someone who deals with reproducible human judgement every day.