The effort required to design something is inversely proportional to the simplicity of the result.
-Roy T. Fielding, http://roy.gbiv.com/untangled/2008/rest-apis-must-be-hypertext-driven
In the context of the article, it is obvious that Mr. Fielding is trying to say that the effort required to design simple things is greater than the effort required to design things that are complex.
Wouldn't "inversely proportional" indicate that if something takes more effort to design, it would be less simple though?
Wouldn't it make much more sense to say:
"The effort required to design something is directly proportional to the simplicity of the result."
or
"The effort required to design something is inversely proportional to the complexity of the result."