Well, guess you didn't expect a literal interpretation of the post title did you? :D
It's my entry for the Contest for the Magento Imagine Conference next month in Los Angeles. Would be great to win one of the great prices in the contest and maybe even get the chance to take a look at the Magento kitchen at the LA Headquarters...
Recently I've seen some (often absolute) statements going around, generally in the line of "open source commerce platforms are a terrible idea". Now of course different solutions always have different pros and cons.
A hierarchy of evidence (or levels of evidence) is a heuristic used to rank the relative strength of results obtained from scientific research. I've created a version of this chart/pyramid applied to CRO which you can see below. It contains the options we have as optimizers and tools and methods we often use to gather data.