A researcher is comparing patients with high medication compliance versus those with low medication compliance in an outpatient psychiatric day program utilizing the Hamilton Anxiety Rating Scale (HAM-A), which has 14 items scored on a scale of 1–4. A higher score on the HAM-A indicates higher levels of anxiety. After collecting the data, she determines the scores obtained in both groups are normally distributed. In the low-compliance group, the mean score is 24 and the standard deviation is 2. In the high-compliance group, the mean score is 16 and the standard deviation is 1.5.

What level of measurement are the instrument items?