Likert scales, levels of measurement and the “laws” of statistics
- Geoff Norman
- … show all 1 hide
Rent the article at a discountRent now
* Final gross prices may vary according to local VAT.Get Access
Reviewers of research reports frequently criticize the choice of statistical methods. While some of these criticisms are well-founded, frequently the use of various parametric methods such as analysis of variance, regression, correlation are faulted because: (a) the sample size is too small, (b) the data may not be normally distributed, or (c) The data are from Likert scales, which are ordinal, so parametric statistics cannot be used. In this paper, I dissect these arguments, and show that many studies, dating back to the 1930s consistently show that parametric statistics are robust with respect to violations of these assumptions. Hence, challenges like those above are unfounded, and parametric methods can be utilized without concern for “getting the wrong answer”.
- Bacchetti, P. (2002). Peer review of statistics in medical research: the other problem. British Medical Journal, 234, 1271–1273. CrossRef
- Berk, R. A. (1979). Generalizability of behavioral observations: a clarification of interobserver agreement and interobserver reliability. American Journal of Mental Deficiency., 83, 460–472.
- Boneau, C. A. (1960). The effects of violations of assumptions underlying the t test. Psychological Bulletin, 57, 49–64. CrossRef
- Carifio, L., & Perla, R. (2008). Resolving the 50 year debate around using and misusing Likert scales. Medical Education, 42, 1150–1152. CrossRef
- Cohen, J. J. (1960). A coefficient of agreement for nominal scales. Educational and Psychological Measurement, 20, 37–46. CrossRef
- Cohen, J. J. (1968). Weighted Kappa; Nominal scale agreement with provision for scaled disagreement or partial credit. Psychological Bulletin, 70, 213–220. CrossRef
- Cronbach, L. J. (1957). The two disciplines of scientific psychology. American Psychologist, 12, 671–684. CrossRef
- Dunlap, H. F. (1931). An empirical determination of means, standard deviations and correlation coefficients drawn form rectangular distributions. Annals of Mathematical Statistics, 2, 66–81. CrossRef
- Fleiss, J. L., & Cohen, J. J. (1973). The equivalence of weighed kappa and the intraclass correlation coefficient as measures of reliability. Educational and Psychological Measurement, 33, 613–619. CrossRef
- Fletcher, K. E., French, C. T., Corapi, K. M., Irwin, R. S. & Norman, G. R. (2010). Prospective measures provide more accurate assessments than retrospective measures of the minimal important difference in quality of life. Journal of Clinical Epidemiology (in press).
- Gaito, J. (1980). Measurement scales and statistics: Resurgence of an old misconception. Psychological Bulletin, 87, 564–567. CrossRef
- Havlicek, L. L., & Peterson, N. L. (1976). Robustness of the Pearson correlation against violation of assumption. Perceptual and Motor Skills, 43, 1319–1334.
- Hunter, J. E., & Schmidt, F. L. (1990). Dichotomozation of continuous variables: The implications for meta-analysis. Journal of Applied Psychology, 75, 334–349. CrossRef
- Jamieson, S. (2004). Likert scales: How to (ab)use them. Medical Education, 38, 1217–1218. CrossRef
- Kuzon, W. M., Urbanchek, M. G., & McCabe, S. (1996). The seven deadly sins of statistical analysis. Annals of Plastic Surgery, 37, 265–272. CrossRef
- Pearson, E. S. (1931). The analysis of variance in the case of non-normal variation. Biometrika, 23, 114–133.
- Pearson, E. S. (1932a). The test of signficance for the correlation coefficient. Journal of the American Statistical Association, 27, 128–134. CrossRef
- Pearson, E. S. (1932b). The test of signficance for the correlation coefficient: Some further results. Journal of the American Statistical Association, 27, 424–426. CrossRef
- Suissa, S. (1991). Binary methods for continuous outcomes: a parametric alternative. Journal of Clinical Epidemiology, 44, 241–248. CrossRef
- Likert scales, levels of measurement and the “laws” of statistics
Advances in Health Sciences Education
Volume 15, Issue 5 , pp 625-632
- Cover Date
- Print ISSN
- Online ISSN
- Springer Netherlands
- Additional Links
- Industry Sectors
- Geoff Norman (1)
- Author Affiliations
- 1. McMaster University, 1200 Main St. W., Hamilton, ON, L8N3Z5, Canada