Academicians criticized those performance measures because they failed to adjust for the relative risk of the mutual fund. Over long periods, as Exhibit 3 shows, different types of securities yielded different levels of total return. Exhibit 4 shows that each of those types of securities was associated with differing degrees of risk (measured as the standard deviation of returns). Tus, the relationship between risk and return was reliable both on average and over time. For instance, it should be expected that a conservatively managed mutual fund would yield a lower return-precisely because it took fewer risks.