- The principles of measuring anxiety are reviewed. Scales of anxiety differ in their time focus: state-anxiety scales measure the present or recent past, whereas trait-anxiety scales measure the ways the subject generally feels. Commonly used scales have adequate validity, but there is incomplete agreement on the boundaries of the construct of anxiety. There are consistent differences in sensitivity among anxiety scales, and they vary greatly in the number of items, number of cues and in the method of scoring. For self-rating scales a large number of items with only two cues (e.g. 'yes' and 'no'), or only two scores for each item, increases the sensitivity of the scale for screening as well as for detecting differences between drug and placebo. A large number of cues decreases the sensitivity of a self-rating scale; it is unknown whether a large number of cues is advantageous in group research, but a small number of items is adequate both for rating and self-rating scales.