Exercise Stress Test. Campbell and Swinscow (2009) describe an experiment in which twenty patients, ten of normal weight and ten severely overweight underwent an exercise stress test. The patients had to lift a progressively increasing load for up to 12 minutes, but they were allowed to stop earlier if they could do no more. On two occasions the equipment malfunctioned before 12 minutes. The times (in minutes) achieved were: Normal weigh 2, 4, 6, a, 8**, 9, 10, 12*, 12*, 12* Overweight 1, 3, 4, 5, 6, 7, 7'\