More on smoking this week: a fairly straightforward trial but notice that it took 61 centres in 10 countries to deliver it. If you're doing research nowadays you need ample administrative skills!
It's worth thinking about the PICO here: Population, Intervention, Comparator, Outcome. The Population were highly selected: people who weren't quite ready to quit, but would give it a go after a period of cutting down. Or as St Augustine put it 1600 years ago: "Give me chastity, O Lord, but not yet.'