The intended purpose and content of types of instruments vary. There are advantages and disadvantages to each of the different type of instrument when used in a particular clinical trial. These criteria are not consistently defined and the literature associated with the criteria cannot be summarised in clear, explicit and unambiguous terms. It is not possible from available evidence to rank order the relative importance of the eight criteria in relation to decisions about selection of measures to include in a trial. Appropriateness requires that investigators consider the match of an instrument to the specific purpose and questions of a trial.
Reliability requires that an instrument is reproducible and internally consistent.
Validity is involved in judging whether an instrument measures what it purports to measure. Responsiveness in this context addresses whether an instrument is sensitive to changes of importance to patients. Precision is concerned with the number and accuracy of distinctions made by an instrument. Interpretability is concerned with how meaningful are the scores from an instrument Acceptability addresses how acceptable is an instrument for respondents to complete Feasibility is concerned with the extent of effort, burden and disruption to staff and clinical care arising from use of an instrument. Conclusions and recommendations is a bullet.