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<<The second biggest flaw is that the study is not statistically valid. Datasnooper (who is famous as this site for exposing the flaws in the "Dogs of the Dow" investing approach recommended in one of the Motley Fool books) has noted that there are not 130 independent data points in the study, but only four (because there are only four 30-year time-periods examined)<snip>>>

If you are quoting Datasnooper correctly (which I seriously doubt owing to your record here) then datasnooper (and you) are DEAD WRONG!!

With 135 years of data. There are 105 THIRTY YEAR ROLLING PERIODS!!! Each and every one is an INDEPENDANT DATA POINT. Only THIRTY data points are needed to make this a statistically significant study. Intercst has done statistical OVERKILL (by a factor of 3.5) on his statistically significant SWR study.

Hocus, PLEASE stop posting about something you know absolutely NOTHING about (i.e. statistics and simple math). You just make yourself look like an idiot.

The "Study" doesn't use any statistics at all, it uses only arithmetic. Anyone who ever downloaded the spreadsheet and looked at it would know this. All it does is state that starting in year 1872, 1873, ..., 19XX, a YY year period of withdrawal will either fail or not fail. Then it tallies up all the failure periods and divides that by the total number of periods to determine what percentage of the periods failed. Thats it.

Usually those failures begin around 1929, and around the mid-to-late 1960's. If you assume that going forwards, there will be a string of YY years that are worse than starting in those above years, then your portfolio will fail.

The "Study" never said anything other than this.
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