In a recent well-publicized opinion, a high-ranking judge sneered at the business valuation profession’s choice of 1926 as the starting date from which to compile market rate of return data, saying that there was nothing special about that year except it was “when Marilyn Monroe was born.” His implication was that this was a purely capricious starting point; i.e. why not choose Hedy Lamarr’s birth year (1913), or something else? Since it was capricious, the results were open to question, right?
Umm, well, with all due respect, Your Hindness, let’s consider the relevant facts, which have nothing to do with birth dates of cinematic icons. The good and kind experts at Ibbotson Associates, an acknowledged, authoritative group of qualified experts, selected 1926 because that was the earliest date that reliable information was furnished to them by the Center for Research on Security Prices at the University of Chicago. The point was to gather a large enough sample (84 years, from 1926 to 2010) of annual observations on rates of return to build strong statistical confidence in the results. That’s good science, not an opinion!
The point, your Onerousness, was that a big sample – 84 observations – means that each one makes up only 1/84th or 1.2% of the sample, so that the importance of any one year’s results, and therefore the selection of the starting year, is minimal. Of course, as we gather more data each year, each year’s importance declines. Long-term data averages out dramatic annual changes and makes the selection of the starting year less and less significant each year.
Moreover, Drudge, the idea of a long-term average is to reflect economic cycles, depressions and growth, recessions, stagflation, peace, war, and population growth, just for starters. We have to do that, because when we capitalize or discount future cash flows, we are using forecasts that extend indefinitely, years and years into the future! We would be dead wrong to apply a single year’s results to the long-term future!
Thank you very much for allowing me to comment.