Validity and reliability of an instrument

Research output: Contribution to journalReview articlepeer-review

2 Citations (Scopus)


Objectives: This paper illustrates the concept of validity and reliability associated with an instrument and how the validity and reliability are assessed. We also included a discussion on how an instrument with unsatisfactory validity and reliability may affect study results, and provide suggestions for certain practical problems encountered by investigators. Methods: We reviewed the literature and provided real-world or hypothetical examples. Results: The level of validity of an instrument is related to the magnitude of systematic errors associated with that instrument, while the level of magnitude of reliability is determined solely by the degree of random errors involved in the measurement. The choices of methods used for the assessment of validity and reliability depend on the attribute of research data. Results from epidemiological studies that used an instrument with non-perfect validity and reliability might entail certain degrees of bias, for which the direction and magnitude are associated with the nature of measurement errors. Conclusions: Researchers should assess, using appropriate methods, the validity and reliability of an instrument before it can be used. This would help to appreciate the potential effects on the study results caused by measurement errors, and lead to correct interpretations of the study results.

Original languageEnglish
Pages (from-to)272-281
Number of pages10
JournalTaiwan Journal of Public Health
Issue number4
Publication statusPublished - 2004 Aug

All Science Journal Classification (ASJC) codes

  • Public Health, Environmental and Occupational Health


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