Set forth below is the text of a comment that I put to an article that my friend Academic Researcher Wade Pfau posted to the Market Watch site:
I am the person who discovered the errors in John Greaney’s safe withdrawal rate study. I put up a post reporting on them at a Motley Fool board that we posted at together on the morning of May 13, 2002, many years before any of the experts in this field were saying that it is not possible to calculate the safe withdrawal rate accurately without taking into account the valuation level that applies on the day the retirement begins.
A fantastic discussion followed in which hundreds of us learned some amazing things about how stock investing works. Unfortunately, John and some others did not want the learning experience to continue and engaged in abusive posting tactics to destroy the board. The comments of hundreds of our fellow community members who wanted this learning experience to continue are detailed in this article:
Wade is familier with this history. I have discussed different aspects of it with him in great depth on numerous occasions.
Stock investing is an intensely emotional endeavor. It is not possible to make sense of any element of the stock investing project without taking the effect of investor emotions on stock prices into account. The P/E10 metric has been shown in research to be the best tool for doing this. There was a time when we didn’t know this but that was 30 years ago. Shiller showed in research published in 1981 that valuations (emotions) must always be considered.
We will not get the SWR (or retirement planning in general) right until we work up the courage to acknowledge that investing is not strictly a numbers game. This is a numbers plus emotions game. P/E10 is the metric that permits us to take valuations into account. It is my strongly held belief that valuation-informed retirement planning strategies are the future.