Correspondence Analysis in BMDP Example

Suicide Method by Age Group and Sex.

From a 1985 study on more than 52,000 suicides in West Germany, data were recorded in a 34 x 8 frequency table—34 sex-age categories and 8 suicide methods. In such a large table it is hard by scanning differences and similarities in row (or column) percentages to understand the relationship between sex, age, and suicide.
In the CA plot of row and column profiles below, each name for 17 male row points begins with M followed by the lower end of its age interval, while the 17 female row points names start with F. Note the male row points line up on the left side and the female points on the right, indicating a clear sex difference in profiles. The vertical dimension shows a rough ranking by age—at the top left, however, the point Male 10-15 years departs from this ordering (and has a smaller sample size). Suicide by hanging and knives is associated with older males; guns, toxic gas, and cooking gas with younger males; poison with young females; drowning with older females; and jumping with old and young females. Points on Axis 1 account for 52% of the information in the table, those on Axis 2, 38%—making total representation of the table as 90%.