I think the distinction is that we /often/ choose not to have a control, for a multitude of reasons, so as a cause for concern it's highly nonspecific. Much lik

I think the distinction is that we /often/ choose not to have a control, for a multitude of reasons, so as a cause for concern it's highly nonspecific. Much like the critique of small samples - there are underpowered 5000-patient multi center trials, and well-powered 30-patient trials. As I said, I think this is a nice introduction but can lead one to discount, well, anything other than large randomized placebo-controlled trials.