问一道题：NO.PZ2017092702000161

问题如下：

Which of the following statistical means best measures a mutual fund’s past performance?

选项：

Harmonic

Geometric

Arithmetic

解释：

B is correct. The geometric mean is an excellent measure of past performance. For reporting historical returns, the geometric mean has considerable appeal because it is the rate of growth or return a fund would have had to earn each year to match the actual, cumulative investment performance. To estimate the average returns over more than one period, the geometric mean captures how the total returns are linked over time.
A is incorrect because the harmonic mean is more appropriate for determining the average price per unit, not evaluating a mutual fund's return history. The average price paid is in fact the harmonic mean of the asset’s prices at the purchase dates. The harmonic mean is applicable when ratios are repeatedly applied to a fixed quantity to yield a variable number of units, such as in cost averaging, which involves the periodic investment of a fixed amount of money.
C is incorrect because the arithmetic mean is more appropriate for making investment statements in a forward-looking context, not for historical returns. It can distort the assessment of historical performance, so it is better applied to estimate the average return over a one-period horizon.