Researchers at a medical school conducted a study to test the effectiveness of a new treatment for lung cancer. Of the 128 lung cancer patients in an affiliated hospital, 94 volunteered for the new treatment, while the remaining 34 declined and underwent traditional treatment instead. The survival rates for the two treatment groups were measured after 12 months.

This study is an example ofan experimental study.

Whether a patient survives after 12 months is the variable. The type of lung cancer treatment is the variable.