Cronbach's alpha is the most common measure of internal consistency ("reliability"). It is most commonly used when you have multiple Likert questions in a survey/questionnaire that form a scale and you wish to determine if the scale is reliable.
Dear Mohammad,
Check my papers out e.g. the attached or those about attitudes towards mental illness. there you see the answers to your question:
Article Student nurses and the general population in Sweden: Trends ...
Hi Mohamed,
You can also refer this RG link on how to calculate Crobach Alpha and Composite Reliability. Wishing you all the best.
https://www.researchgate.net/post/Hi_Buds_please_Im_actually_doing_my_survey_and_would_like_to_use_Cronbachs_alpha_to_ensure_reliability_Could_you_advise_how_to_use_that_tool
Hello Mohamed,
Just a wee addition. Anything above Cronbach's alpha of .7 is good, slightly below acceptable (possibly .65).
Regards, Witold
Dear Mohammad,
Cronbach's alpha is a measure of internal consistency, that is, how closely related a set of items are as a group. It is considered to be a measure of scale reliability. Cronbach's alpha usually uses SPSS or MS excel :
SPSS: http://www.ats.ucla.edu/stat/spss/faq/alpha.html
MS Excel: http://www.real-statistics.com/reliability/cronbachs-alpha/
the acceptable values should be more than (60%) according to (Sekaran, 2006, 311). or 70% in other sources, therefore the value exceeding the foregoing proportion indicates that the a survey/questionnaire is reliable.
Sekaran, U. (2006). Research methods for business: A skill building approach. John Wiley & Sons. New York.
Good Luck!
Salah
When we have likert scale, all the items are selected for the reliability analysis. this also can be done on the subscales level.
the Cronbach’s Alpha reflects how much the items are correltated, and measure the one idare, and all items are in the same direction.
it is prefered to have the reading .70 and higher
However, just very recently found out that very high Cronbach's alpha MAY indicate multidimensionality....
Shevlin, M., Miles, J. N. V., Davies, M. N. O., &Walker, S. (2000). Coefficient alpha: A useful indicator of
reliability? Personality and Individual Differences, 28, 229-237.
Regards
I agree with Alvin Vista: Cronbach's alpha is not adequate for estimating the internal consistency of Likert scales. It is the most commonly used, but not correct. It must be used other statistics, such as Carmines' Theta and Heise and Bohrnstedt's Omega. The three are related, but maintain a relationship α < θ < Ω. It is advisable to inform about the three values.
doi: 10.1080/17437199.2015.1124240.
10.1080/17437199.2015.1124240
First, a minor point to consider. Instruments, scales, etc are not reliable. Scores are reliable; thus, the correct designation is "score reliability of the scale." Next, Dr. Bezirgani and others have referred directly or indirectly to the "empirical value of the scale." One generally runs a factor analysis of the data first then proceeds from there with the reliability analysis. I know this means more work; however, you might consider a factor analysis first in your study.
Is there any literature to which I can refer for reversals and deletions on the reliability scales using the cron bach alpha test? I am writing on my pilot study and need a credible source for this information. Also a source that states the rationales for reversals and deletions. I need to justify the actions taken after the reliability tests were run. Looking forward to your responses.
These links may help you:
http://psych.hanover.edu/classes/ResearchMethods/Assignments/reliability-1.html
http://www.statsdirect.com/help/content/regression_and_correlation/pca.htm
http://www.statstutor.ac.uk/resources/uploaded/spssguide1mar2012.pdf
http://www.stata.com/manuals13/mvalpha.pdf
https://www.medcalc.org/manual/cronbach_alpha.php
Sorry Ana Bezirgani and Shamin Ally, but Cronbach's alpha is not an appropriate measure for Likert scales, at least in the way that gets the SPSS. The lineal Cronbach's alpha is obtained from the Pearson correlations, which are only applicable to continuous data. The Likert scale is not continuous, but an ordinal categorical scale. Although it is usual to find it in the bibliography, a demanding reviewer would reject your work if you use that test in your data. There are other alternatives, although they must be obtained in ways that are not available in SPSS: from the matrix of polychoric correlations and apply the ordinal alpha, McDonald's omega or others. I attach some links that can serve as an overhead.
http://digitalcommons.wayne.edu/cgi/viewcontent.cgi?article=1121&context=jmasm
http://www.pareonline.net/getvn.asp?v=17&n=3
it very important to use Alpha when you wan to know the relationship between two or more variables. and most commonly measure to use Alpha ( if the reliability is more 78% you are able to. to contineous your research )
Hello Everyone,
I have a question about reporting Cronbach's alpha. I am not sure how to begin. In the process of writing a paper and was instructed to report alpha. the three reliability scores were .84, .85 and .86. How does this translate into Cronbach alpha in APA format?
Cronbach's alpha = .84; Cronbach's alpha = .85; Cronbach's alpha = .86; Cronbach's alpha= .84;.85 and .86
or internal consistency (Cronbach's alpha= .84;.85 & .86)
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