A recent study suggests that the onset of Alzheimer’s disease (AD) is related to exposure to microorganisms.24 A greater exposure to microorganisms may actually protect against AD. A random sample of...

A recent study suggests that the onset of Alzheimer’s disease (AD) is related to exposure to microorganisms.24 A greater exposure to microorganisms may actually protect against AD. A random sample of countries was obtained and a measure of contemporary parasite stress (x) and AD burden (y) was recorded for each. The data are given in the following table.