Old thread, but it comes up first when you search for this, so it is worth updating. One habit that pays for itself: post the method alongside the number. A figure without its method cannot be checked, and an unchecked figure is how this community accumulates folklore.

That is the short version; the long version is somebody else's post.

quinn_sf said:

The boring version of this is the one that works, and the boring version is: measure a baseline, change one variable, wait, measure again under the…

True, with the qualification that this is a self-selected group. The people for whom it did not work post less, and that shapes everything we think we know.