Chapter 12 Objective questionnaires for assessment sleep quality

Rating scales play an important role in clinical practice and research. They can be used to assist in determining the nature of patients' problems to chart any changes in their condition, and as outcomes in sleep studies. Constructing a useful scale is a multistage process. The first is to devise the items that will constitute the scale. The items then need to be checked to determine if they are understandable and free from any biases. Furthermore, the items must cover all important aspects of the domain, while at the same time not include any irrelevant content. Then, it is necessary to determine if the scale is reliable; that is, if the same score is obtained on two occasions, or if two raters evaluate the same patient. Finally, the validity of the scale needs to be assessed within the group to which it will be applied. This chapter can be read both by those contemplating devising their own scales, as well as those who wish to assess the usefulness of existing scales.