Decreasing returns to sampling without replacement
研究了从有限总体中无放回抽样寻找极值（最低或最高值）时的回报递减性质，证明了期望最小值是样本量的递减且离散凸函数，并给出了其他顺序统计量成立该性质的充分条件。
We study sampling from a finite population without replacement when seeking an extreme (lowest or highest) value. An example is a buyer searching for the lowest price. It is well known that there are decreasing returns to sampling from continuous populations: the expected minimum is a decreasing and discretely convex function of the sample size. We show that this holds when sampling without replacement from a finite population. We also state a sufficient condition on population values for the properties to hold for other order statistics.