ABSTRACT
There was a leak of the gas Cyadmine4 at a chemical works and the gas cloud hung over the town of Newtoncastle for a number of days before dispersing into the atmosphere. There were some complaints of sore throats amongst the townspeople but the chemical company assured the public that there are no adverse effects of Cyadmine on the human body. However, a scientist who worked on the Cyadmine project has gone on record as saying that Cyadmine could have an effect on pregnant women and their unborn children. The company has dismissed the scientist’s claim as nonsense, noting that the scientist was unable to specify what problems could arise. There is not a universal confidence in the chemical company and there is some concern in the affected areas especially from parents of young children. A doctor in the large maternity hospital has been keeping an eye on babies born in the nine months after the cloud passed over the town. She has noted that the babies appear healthy on all the usual checks but is suspicious that the Cyadmine could have affected their birth-weights as many of the babies appear rather small at birth. The doctor is worried about any long-term effects and wants to test whether the ‘Cyadmine babies’ are smaller at birth than usual. Essentially, the doctor is making a one-tailed prediction: the distribution of the birth-weights of the Cyadmine affected population will be different to the distribution of the birth-weights of the unaffected population with the overlap of the distributions occurring at the lower end of the unaffected distribution.
