Manure can vary from a lot of straw with a little ordure, to a lot of ordure with a little straw.
Bandolier would like to advocate this evolving checklist for sniffing out the good from the bad when it comes to single trials of effectiveness. The smaller the number, the less credible the result. If there are small differences which are only of statistical significance, forget it. Goal post moving should worry you. Examples are failure of treatment explained by not treating the disease early enough, and if lots of adverse effects are associated with a particular intervention, the protagonists then argue that of course they have now improved their technique.