>I am looking for a good
>explanation of whether or not
>a fourfold increase in something
>means the same as a
>400 percent increase or a
>4 times increase or not.
>This applies to any number
>obviously. I am a science
>writer and this pops up
>all the time in technical
>and business stuff and nobody
>can give me a reasonable
>answer.

I may refer you to an authority on that matter: Edward MacNeal.
Visit this site:

http://www.mathsemantics.com

You may be surprised to find out that the interpretation is not unique and that some interpret 4 times increase as "4 times as much" while others as "5 times as much."

My personal interpretation is that 400% increase points to an additive procedure: 100% + 400% = 500%, whereas "increase of 4 times" points to a multiplicative procedure 1·4 = 4 or 100%·4 = 400%.