Using this information and the formula above, we can calculate the AAR for the period from 2000 to 2003:
AAR = (20% + 25% + 22% + 1%) / 4 = 17%
Why It Matters
AAR is somewhat useful for determining trends. However, because returns compound (they generally not add) AAR is typically not regarded as a correct form of return measurement and thus it is not a common formula for analysis.
In addition, one or a few particularly high or low data points ("outliers") can skew the average and provide misleading results. Thus, most analysts prefer to use the compound annual growth rate (CAGR) when evaluating changing returns.