You get concerned about the blood pressure readings, so you take 5 more. They range in value from 136/84 to 142/90 mmHg, and only two are exactly the same. You then call in your tutor, and she takes 5 measurements that are all exactly the same at 138/88 mmHg. You also ask your nurse to monitor this patient, and he takes 5 readings that vary between 140/90 and 150/94 mmHg.

Measures that are taken by the same person or "rater" are called "intra-rater" measurements or observations. Measures that are taken by different raters are called "inter-rater" measurements.