These are data from nine randomized trials on preventing pre-eclampsia
in women with a diuretic treatment compared to a control. treat = 1 
denotes the diuretic while treat = 2 denotes the control. The data
show how many women in each trial on each treatment had pre-eclampsia.

The data were reported on in Collins R, Yusuf S, and Peto R (1985).
"Overview of randomized trials of diuretics in pregnancy," British
Medical Journal, 290: 17-23.

The data were again examined in Thompson SG and Pocock SJ (1991). 
"Can meta-analyses be trusted?," Lancet, 338: 1127-1130.

Data source: Brown H and Prescott R (1999). Applied mixed models in
medicine. Chichester, England: John Wiley & Sons, Inc.