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URL:  http://boards.fool.com/one-of-the-problems-i-have-with-the-trinity-study-11210351.aspx

Subject:  Re: Burn Rate Date:  8/31/1999  1:08 PM
Author:  rjm1 Number:  13558 of 76392

One of the problems I have with the Trinity study is that it assumes an average
market rate of return. What happens if we instead put our money in the Foolish
Four or RP4 or whatever we call it these days? It seems to me that if the
average rate of return goes up, the acceptable withdrawal rate should also
increase. I don't think it is the same percentage increase because the standard
deviation of the FF is higher than the market, so the computation is complicated.

I personally like the constant % of the value of the portfolio method. Most
people will also get some Social Security, so there is a fixed "floor" income and
the % variation in total income is dampened by this. The other rerason I like it is
that the idea of projecting a constant inflation rate over 35 years has a large
chance of giving a result which does not at all correspond to reality.

The other issue I have with studies like Trinity is that they do not consider the
chances for a "mid-course correction". I for one, do not intend to retire, set up
my portfolio, and then never have another financial thought for the rest of my life.
I will monitor my investments and make minor changes as necessary.


The problem is with all studies. You have to make assumptions about the market which may not match your results. The studies also assume the same pattern of stockmarket returns as in the past. The costs of investing is also missing in some cases. If I did a study to be published mine would have the same problems.

But when I figure out my retirement plan I want it to work. I have used Quicken for years and can get my actual before tax return on my investments. About 10 to 11%. (guess you can tell I am not in my 20's). What I can not do is project the actual returns that will be achieved in the future. Therefore I took 10 year patterns from investment indexes and mixed them to see how my future growth would be affected. I also adjusted the first year or two for large market declines as I think this is the bigest risk. This helps give you insite into what the proper withdrawl rate is but no one will know until it is over.
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