The runs that left before the counting started
Ask what left before the counting started, because whatever fell out on the way does not appear anywhere in the answer.
This is the second of the three, it is the least glamorous question in the volume, and in my experience it is the one most often fatal. It is also the one nobody thinks to ask, because it is a question about an absence and absences do not appear on slides.
Runs fail. They error, they time out, they come back empty, they hit a rate limit, they crash on an input nobody expected. Every one of those is an outcome, and every one of them has to go somewhere. There are exactly two places it can go: counted as a failure, or removed before the counting started.
The effect on the share has no upper bound, which is what makes this different from the other seven questions. A small count merely widens your doubt. Dropped failures move the figure in one direction, by as much as you like, while every individual calculation along the way remains correct.
Two kinds of absence, one question
| what is missing | how it happens | what to ask |
|---|---|---|
| runs that did not finish | an error is not a verdict, so the row has nothing to score and quietly leaves | how many runs did not produce an answer, and where are they in this number? |
| situations with no case at all | nobody wrote a case for the thing that only happens at quarter end | which of the situations we actually care about has no case here? |
The tell is a suspiciously round count. Real runs produce ragged numbers. A set of cases that started at some round figure and reported a result over exactly that same round figure means nothing errored, nothing timed out, and nothing was excluded — which happens, but is worth one question.
The good answer is specific and slightly embarrassing: a handful errored, here is why, we scored them as failures. Someone who has looked will tell you this without being pushed. Someone who has not will tell you it did not come up.