In my opinion, the single best study on this topic was conducted by Prof.

FORBES: What the NRA is Assuming (and Why They are Wrong)

Like much of the previous research on coffee, the study was based on survey data -- in this case, a single questionnaire distributed in the mid-1990s -- that may provide an incomplete picture of the participants' overall health and lifestyle.

CNN: Coffee drinking linked to longer life

The FDA based its approval of the NovoTTF 100A System on results from a single international clinical study in 237 patients with recurrent GBM or with GBM that hadn't responded to traditional therapy.

ENGADGET: Portable brain tumor treatment system kills cancer while you take out the trash

He believes that a study done ten years earlier by an academic researcher on a single subject could have foretold the events with TGN1412.

FORBES: Bad Pharma? Maybe. But Goldacre's Selective Use of Data Is Wrong

One disease under study is cystic fibrosis, which is caused by one of around 200 defects on a single gene.

ECONOMIST: Animal rights extremists