References
- Farivar S, Liu H, Hays R. Another look at the half standard deviation estimate of the minimally important difference in health- related quality of life scores. Expert Rev Pharmacoeconomics Outcomes Res. 4(5) 515–523 (2004).
- Norman G, Sloan J, Wyrwich K. Interpretation of changes in health-related quality of life: the remarkable universality of half a standard deviation. Med. Care 41, 582–592 (2003).
- •• Reviews current studies that investigated minimal important differences and reported the magnitude of these differences in terms of effect size. There is a consistent mean effect size result of 0.5 standard deviations across all studies and among the many ways that the reviewed studies are subgrouped.
- Erder M, Hays R, Santanello N. Assessing the clinical significance of patient-reported outcomes: examples drawn from a recent meeting of the drug information association (DIA). Clin. Ther. 25, D12—D13 (2003).
- Miller G. The magic number seven plus or minus two: some limits on our capacity for processing information. Psychol. Rev 63, 81–97 (1956).
- •• Classic 1956 paper notes that across a wide range of unidimensional discrimination tasks (e.g., saltiness of tastes, points on a line, pitch and loudness of sounds), the limit of people's abilities to make absolute discriminations turned out to be very consistent, that is, people were capable of identifying the category of a particular stimulus (i.e., loudness of sounds and saltiness of tastes) accurately until the number of categories reached approximately seven (with a range from —5 to 9). Argues that this uniformity derives from a fundamental characteristic of human information processing that was called channel capacity, related indirectly to limits on short-term memory.
- Goldstein R, Gort E, Stubbing D, Avendano M, Guyatt G. Randomised controlled trial of respiratory rehabilitation. Lancet344, 1394–1397 (1994).
- Guyatt G, Berman L, Townsend M, Pugsley S. Quality of life in patients with chronic airflow limitations. Br. .1. Dis. Chest 81,45–54 (1987).
- Jaeschke R, Singer J, Guyatt G. Measurement of health status: ascertaining the minimal clinically important difference. Controlled Clin. Trials 10,407–415 (1989).
- ••Often serves as the unofficial guidelinesfor minimal (clinically) important difference studies in health-related quality of life measures.
- Kosinski M, Zhao SZ, Dedhiya S, Osterhaus JT, Ware JE Jr. Determining minimally important changes in generic and disease-specific health-related quality of life questionnaires in clinical trials of rheumatoid arthritis. Arthritis Rheum. 43(7), 1478–1487 (2000).
- ••This detailed study of the minimallyimportant difference for the Short Form-36 and the HAD scales among persons with rheumatoid arthritis reveals the span of magnitudes for the minimally important difference that can result from differing criteria for defining an important change.
- Ware J Jr, Snow K, Kosinski M, Gandek B. The SF-36 Health Survey Manual and Interpretation Guide. The Health Institute, New England Medical Center, Boston, MA, USA (1993).