The data for this example come from a study of the effects of childhood sexual abuse on adult females. 45 women being treated at a clinic, who reported childhood sexual abuse, were measured for post traumatic stress disorder and childhood physical abuse both on standardized scales. 31 women also being treated at the same clinic, who did not report childhood sexual abuse were also measured. The full study was more complex than reported here and so readers interested in the subject matter should refer to the original article.
The variables in the dataset are
Childhood physical abuse on standard scale
Post-traumatic stress disorder on standard scale
Childhood sexual abuse - abused or not abused