In a random sample of 100 patients with biopsy-confirmed breast cancer, a study examines cancer detection rates with 50 previously collected, two-dimensional (2D) mammograms compared to detection rates in 50 previously collected, three-dimensional (3D) mammograms. The alpha selected for this pilot study is 0.10, and the power is 0.80.

If cancer detection is measured as yes or no, what level of measurement is this variable?