"The 4% retirement rule ... is based on multiple studies that included using Monte Carlo analyses"
What the WSJ article says: "Based on pioneering research in the early 1990s by William Bengen, then a financial planner in California, the so-called 4% rule states that retirees can pull about 4% annually from their nest egg (a figure
Mr. Bengen eventually set at 4.5%), with a high probability that their savings will last 30
years."
Bengen's research had nothing to do with Monte Carlo analyses, such as "This Vanguard Monte Carlo calculator."
Bengen said so himself: "Let me add that I am a great admirer of Vanguard and their effort to serve investors well with low-cost, well-managed funds. I use their funds in my personal portfolio. But our approach to computing "safe" withdrawal rates ... is quite different."
https://www.aaii.com/journal/article/insights-on-using-the-withdrawal-rule-from-its-creatorThat excellent 2018 interview with Bengen was linked to by the WSJ article. To me what is interesting is not so much the 4% figure as why he picked a thirty year target. (FWIW, in 1994, the
IRS joint life table for a couple of 65 year olds was 25
years. The
current Table III shows 27.4
years for a 70 year old couple, so we can assume that a 65 year old couple would have at least a 30 year life expectancy per IRS today).
Also, in his followup that I quoted from above, he addressed
@slick's 3.5%
In contrast, my methods use actual historical returns and inflation rates in the order in which they occurred. Vanguard's methods create sequences of returns and inflation which probably never happened in reality. As a result, they may generate "worst case" scenarios worse than anything that has ever happened, while my methods search for the worst case that has actually occurred.
Note also that Vanguard uses different asset classes than I do in my research.
When you change things like that, numbers can change radically.