Today I posted a blog about Apple not allowing to sell physical products through an iPhone app. Gladly, I was wrong. I was looking at the Getting Started with In App Purchase on iPhone OS guide which refers to the 'In App Purchase system'. It's true that you can't use that to sell a physical product because of Apple regulation. But you don't need the whole 'In App Purchase' in the first place! So really my bad, but that means there's nothing holding you back from selling huge amounts of clothing, hardware, shoes, lawn mowers (or whatever you sell) through an iPhone app! Great thing to be wrong about :)
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.