Objective: To assess the properties of validity and reliability of instruments used to assess satisfaction in a broad sample of health service user satisfaction studies, and to assess the level of awareness of these issues among study authors.
Design: Examination and analysis of 195 papers published in 1994 in 139 journals. The following databases were searched: British Nursing Index, CINAHL, EMBASE, MedLine, Popline, and PsycLIT.
Main measures: Number and types of strategies used for content, criterion, and construct validity, and for stability and internal consistency. Associations between validity/reliability and other study characteristics.
Results: Eighty-nine (46%) of the 195 studies reported some validity or reliability data; 76 reported some element of content validity; 14 reported criterion validity, with patient's intent to return the most commonly used criterion; four reported construct validity. Thirty-four studies reported internal consistency reliability, 31 of which used Cronbach's coefficient alpha; eight studies reported test-retest reliability. Only 11 studies (6% of the 181 quantitative studies) reported content validity and criterion or construct validity and reliability. 'New' instruments designed specifically for the reported study demonstrated significantly less evidence for reliability/validity than did 'old' instruments.
Conclusion: With few exceptions, the study instruments in this sample demonstrated little evidence of reliability or validity. Moreover, study authors exhibited a poor understanding of the importance of these properties in the assessment of satisfaction. Researchers must be aware that this is poor research practice, and that lack of a reliable and valid assessment instrument casts doubt on the credibility of satisfaction findings.