EoC # 12 - specified in advance - validity of benchmark

In this question…kim lee says that the benchmark for performance is to be in the top quartile of its peer group over the previous calendar year.

why is this not a valid benchmark?

it says in the answer that this benchmark can not be specified in advance. i do not understand, because it says in the question explicitly PREVIOUS quarter, so what is the issue here?


I will beat the top ranker of all time …

kind of like that.

who is it?

what is their style?

is it relevant to my style (that I want to beat).

it will continously change so it can’t be specified in advance like, say, the S&P 500 which stays constant

you don’t know who was in the top quartile until the results are already posted.

thus it cannot be specified IN ADVANCE or ex-ante to the period of performance.