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For example, an all-bond index portfolio has provided a small but consistent return, while an all-equity index portfolio has provided a larger but more erratic return. Higher expected returns are the reward for an investor’s willingness to accept this volatility. In other words, risk is the source of returns and, therefore, should be embraced in appropriate doses.

stAndArd devIAtIon of returns An effective and common method to measure the deviation of investment returns from the average is the standard deviation of returns. Standard deviation provides a statistical measure of historical volatility and sets forth a distribution of the ranges of probable outcomes. In investing, measuring standard deviation of returns shows the extent to which returns (daily, monthly or annual) are distributed around the average return, estimating a range of probable outcomes and establishing a framework of risk and return trade-offs. The normal distribution in the form of a bell-shaped curve shown in Figure 8-1 illustrates the concept of standard deviation. The curve represents a set of outcomes. In this case, let’s say the outcomes are the monthly returns of an investment. The yellow area covered in one standard deviation away from the average in both directions accounts for approximately 68% of the outcomes in a period. The area within two standard deviations from the average, the yellow and green shaded areas, accounts for 95.6% of outcomes, and the area up to three standard deviations away from the average-illustrated by the yellow, green and orange shaded areas-accounts for 99.7% of

Index Funds: The 12-Step Recovery Program for Active Investors  

This book reveals the potential land mines and pitfalls of active investing and educates readers on the benefits of passive investing with i...

Index Funds: The 12-Step Recovery Program for Active Investors  

This book reveals the potential land mines and pitfalls of active investing and educates readers on the benefits of passive investing with i...