How can we use the chi-square contingency test on a matrix with two categories?
In statistics, contingency tables are used to record and analyze the relationship between two or more variables, most usually categorical variables. This is the most efficient way to represent cross-categorized frequency data.Here is a concrete example of cross-categorized frequency data, adapted from a medical study that sought to determine whether estrogen supplementation might delay or prevent the onset of Alzheimer’s disease in post-menopausal women.The subjects in the study were 1,124 post-menopausal women who were initially free of Alzheimer’s disease, Parkinson’s disease, and stroke, and who were taking part in a longitudinal study of ageing and health in a New York City community. Of these women, 156 had received estrogen supplementation following the onset of menopause, while the remaining 968 had not. The following table breaks these two groups down according to whether the women did or did not show signs of Alzheimer’s disease onset during a five-year follow-up period, as ju
