FundAdvice.com - How much money can you prudently take out of your investments in retirement?
Paul Merriman compares how a fixed withdrawal strategy (ie. % of initial portfolio adjusted for inflation annually) would do v/s a variable withdrawal strategy (ie. fixed percentage of current portfolio value).
I found the data interesting because while taking variable withdrawals may sound good, the swings can be pretty painful (as I experienced in 2008). Interestingly, he has taken expenses into account as well as a 1% management fee. You don't see data with expenses included very often.
Paul's suggestion is to save enough to "afford" a variable SWR. ie, have your initial withdrawal be more than what you need, so that you will be able to do more than survive if the withdrawals decrease for a period of time.
(I apologize if this document was already linked to in another post. I read it someplace but can't find the post here or on bogleheads.)