London: Sage Publications Ltd.ДЇishbein, M., & Ajzen, I. From alpha to omega: A practical solution to the pervasive problem of internal consistency estimation. Coefficient alpha and the internal structure of tests. Journal of Applied Psychology, 78(1), 98вЂ“104.Д¬ronbach, L.

What is Coefficient Alpha? An Examination of Theory and Application. San Francisco, CA: Jossey-Bass.Д¬ortina, J. Planning health promotion programs: an Intervention Mapping approach (3rd ed.). In this contribution, I will explore these issues, and provide recommendations for scale inspection that takes these dynamics and this distinction into account.Д«artholomew, L. This requires forgoing the appealing comfort of a quantitative, seemingly objective indicator of scale quality altogether, instead acknowledging the dynamics of reliability and validity and the distinction between scales and indices. Solving the second problem, however, is less straightforward. The problems with CronbachвЂ™s alpha are easily solved by computing readily available alternatives, such as the Greatest Lower Bound or Omega. Second, the approach itself assumes that scale items are repeated measurements, an assumption that is often violated and rarely desirable. First, CronbachвЂ™s alpha is both unrelated to a scale's internal consistency and a fatally flawed estimate of its reliability. Unfortunately, this approach suffers two fundamental problems. CronbachвЂ™s alpha is often viewed as some kind of quality label: high values certify scale quality, low values prompt removal of one or several items. Health Psychologists using questionnaires rely heavily on CronbachвЂ™s alpha as indicator of scale reliability and internal consistency.

Validity and reliability in psychology