送交者: wasguru 于 2006-4-05, 16:41:40:
回答: It is easy to prove Mean-SE=0 given (在所有数据=0的前提下） 由 秦州刺史 于 2006-4-05, 14:00:41:
MEAN - SE \gt;=0, which is pretty easy. And the equality holds when there's only one data point greater than 0.
For other cases, simply substract MIN(X) from each data point. This operation shifts the MEAN and MIN by the same amount, and does not affect SE. So the inequility still holds. In particular, the equality hold when there's only one data point greater than the minimum. Your "counter example" satisfies the condition, therefore the exact MEAN-SE must be 0.1. Your observeration is indeed due to numerical error