Researchers randomly assigned metastatic breast cancer patients to either a control group or a group that received weekly 90 minute sessions of group therapy and self-hypnosis, to see whether the latter treatment improved the patients' quality of life.
A data frame with 58 observations on the following 3 variables.
months of survival after beginning of study
a factor with levels
0 if entire lifetime observed, 1 if patient known to have lived at least 122 months
Ramsey, F.L. and Schafer, D.W. (2013). The Statistical Sleuth: A Course in Methods of Data Analysis (3rd ed), Cengage Learning.
Spiegel, D., Bloom, J.R., Kraemer, H.C. and Gottheil, E. (1989). Effect of Psychosocial Treatment on Survival of Patients with Metastatic Breast Cancer, Lancet 334(8668): 888–891.