E-ISSN 2636-834X
 

Original Research 


Sample Size in Reliability Studies: A Practical Guide Based on Cronbach's Alpha

Sevinc Puren Yucel Karakaya, Zeliha Nazan Alparslan.

Abstract
Objective: Internal consistency of scales is crucial for the quality of clinical practices, and scales that measure various aspects of clinical disorders must possess acceptable internal consistency. In the assessment of the internal consistency of the scales, the present study considered the Cronbach’s alpha’s coefficient. This study aims (1) to provide a practical sample size guide based on Cronbach’s alpha for medical researchers; (2) to investigate the factors related to the determination of the sample size needed for a correct estimation of Cronbach’s alpha.
Method: The calculation steps of the two sample size approaches (desired precision and desired power) proposed by Bonett are detailed and the sample size tables of these approaches are tabulated.
Results: Findings indicate that as the number of items in the scale increases, the sample size decreases to a certain level but reaches a plateau when the number of items is about 30. Furthermore, it is claimed that the sample size should be at least 45 (and more) in order to calculate a meaningful internal consistency coefficient.
Conclusions: In the present study, we extracted detailed information about the key components of sample size calculation for Cronbach’s alpha and provided an easy and practical tables, which will enable clinicians to determine the appropriate sample size for their internal consistency studies.

Key words: Internal Consistency, Cronbach's Alpha, Sample Size, Precision, Power.


 
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How to Cite this Article
Pubmed Style

Karakaya SPY, Alparslan ZN. Sample Size in Reliability Studies: A Practical Guide Based on Cronbach's Alpha. PBS. 2022; 12(3): 150-157. doi:10.5455/PBS.20220127074618


Web Style

Karakaya SPY, Alparslan ZN. Sample Size in Reliability Studies: A Practical Guide Based on Cronbach's Alpha. https://www.pbsciences.org/?mno=18637 [Access: October 02, 2022]. doi:10.5455/PBS.20220127074618


AMA (American Medical Association) Style

Karakaya SPY, Alparslan ZN. Sample Size in Reliability Studies: A Practical Guide Based on Cronbach's Alpha. PBS. 2022; 12(3): 150-157. doi:10.5455/PBS.20220127074618



Vancouver/ICMJE Style

Karakaya SPY, Alparslan ZN. Sample Size in Reliability Studies: A Practical Guide Based on Cronbach's Alpha. PBS. (2022), [cited October 02, 2022]; 12(3): 150-157. doi:10.5455/PBS.20220127074618



Harvard Style

Karakaya, S. P. Y. & Alparslan, . Z. N. (2022) Sample Size in Reliability Studies: A Practical Guide Based on Cronbach's Alpha. PBS, 12 (3), 150-157. doi:10.5455/PBS.20220127074618



Turabian Style

Karakaya, Sevinc Puren Yucel, and Zeliha Nazan Alparslan. 2022. Sample Size in Reliability Studies: A Practical Guide Based on Cronbach's Alpha. Psychiatry and Behavioral Sciences, 12 (3), 150-157. doi:10.5455/PBS.20220127074618



Chicago Style

Karakaya, Sevinc Puren Yucel, and Zeliha Nazan Alparslan. "Sample Size in Reliability Studies: A Practical Guide Based on Cronbach's Alpha." Psychiatry and Behavioral Sciences 12 (2022), 150-157. doi:10.5455/PBS.20220127074618



MLA (The Modern Language Association) Style

Karakaya, Sevinc Puren Yucel, and Zeliha Nazan Alparslan. "Sample Size in Reliability Studies: A Practical Guide Based on Cronbach's Alpha." Psychiatry and Behavioral Sciences 12.3 (2022), 150-157. Print. doi:10.5455/PBS.20220127074618



APA (American Psychological Association) Style

Karakaya, S. P. Y. & Alparslan, . Z. N. (2022) Sample Size in Reliability Studies: A Practical Guide Based on Cronbach's Alpha. Psychiatry and Behavioral Sciences, 12 (3), 150-157. doi:10.5455/PBS.20220127074618