Cronbach's Alpha: What Does α = .70 Really Mean?
You run your reliability analysis in SPSS, and there it is: Cronbach's alpha = .68. Now you are wondering: “Is my questionnaire unreliable? Do I need to throw away the scale? Will my supervisor or journal reviewer reject my study?” Not so fast. A Cronbach's alpha below .70 deserves attention, but .70 is not a magical pass-or-fail line . The meaning of an alpha coefficient depends on the number of items, how closely the items are related, the nature of the construct, the purpose of the research, and the evidence that the scale is measuring a coherent construct. In this article, we will look at what Cronbach's alpha actually tells you, what α = .70 means, what to do when you obtain something like α = .68 , and the mistakes you should avoid when reporting reliability in a thesis or journal article. Quick answer: An alpha of .70 is commonly used as a rule-of-thumb benchmark for acceptable internal consistency, but it should not be treated as a universal cutoff. A...