# Classifying errors

In the latest episode of EconTalk, Russ Roberts mentions Jens Rasmussen’s classification of errors into three categories: slips, mistakes, and violations.

So, a slip is: you just do something you immediately realize wasn’t what you meant to do — pushed the wrong button, locked yourself out of your house, forgot your car keys. Mistakes are things you do because your view of the world is wrong. So, you took out a subprime mortgage and bought a house because you thought house prices would continue to rise and you would be able to remortgage your house. Then there’s a violation — something you know is against the rules but you did it anyway, for whatever reason.

Perhaps it would be useful to classify errors more continuously based on how long it takes to regret them. For example, you might know you’ve made a slip a split second later. It typically takes longer to realize you’ve made a mistake. And violating a regulation, assuming it’s a wise regulation, may not lead to negative consequences for quite some time.

## 9 thoughts on “Classifying errors”

1. Juan Castaneda

How many dimensions are there in a space where we could measure the distance between intention, and consequences? A small slip can lead to catastrophic consequences. However, both the magnitude of the slip itself, and that of its consequences are still relatively independent of the time it takes to realize you made a slip. Another thing, sometimes two mistakes cancel each other out, so luck plays a role, too. And as far as regretting the mistake, that is kind of subjective because two different people can make the same mistake, both with the same unwanted consequence but it’s possible that each will regret it in a different measure, at a different time. I suspect these topic of mistakes is too close to real-life reality to have a simple mathematical model that covers most of its aspects.

2. Mistakes are caused because you don’t know something, so there are two kinds of mistakes, the ones that are caused by known unknowns (in this case it may take some time, but eventually you’ll realize you made a mistake) and unknown unknowns – in which you may never understand you made a mistake,you’ll just have an invisible distortion that you may be the only one that don’t notice.

3. Then what’s a boo-boo?

4. So if I never regret my actions, I never make any errors…

5. Scott

Violations can have immediate consequences, either expected – take what you want and pay for it – or unexpected: duh.

6. I like the taxonomy, but I’m not quite sure where diagnostic errors–false positives and false negatives–fit in. After all, we know in advance we’re going to have some of these, so they’re neither slips nor mistakes, and I don’t think we’re deliberately breaking a rule, either….

7. EastwoodDC

> So if I never regret my actions, I never make any errors…

Also if you never correct your errors, whether you know you committed them or not.

There is also the degree of error. Maybe you took out a subprime mortgage, but were able to get out of it with relatively little loss. Maybe you didn’t buy the house, but you should have. The statistical concepts of Type I and II errors seem to apply.

8. Apropos of nothing, I spotted this wisecrack:

I don’t need to test my programs. I have an error-correcting modem.
– Om I. Baud

9. Paavo Ojala

Wasn’t it Tim Harford, who mentions Jens Rasmussen, not Russ Roberts. It’s