In the past year Harborville has had an unusually high rate of new cases of a certain disease  An investigation revealed that over the past five years Harborville' s public water supply has had a high level of pollutants
Medical researchers have hypothesized that Harborville' s water is responsible for the high rate of new cases of the disease
Most of the people afflicted with new cases of the disease had regularly drunk larger quantities of Harborville's water than had other Harborville residents.