In addition to my Magento Community 1.7 and Enterprise 1.12 New Features Walkthrough: Magento also published a new User Guide for the Community 1.7 edition. You can now download it, free of charge from magento.com. It looks like Magento has put great effort in this to make and completely updated the guide with new screenshots and information, and not just added info about the newly added features. With the 291 pages and 10,0 MB pdf file they are really living up to their promises that one day, we'll be complaining about how much documentation there is for Magento... ;)
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.