Only one cluster per condition is an invalid design for a cluster randomized trial and should be re-labeled a quasi-experimental study. Response to: "Effect of behavioral activation on time and frequency domain heart rate variability in older adults with subthreshold depression: a cluster randomized controlled trial in Thailand"
Explains why assigning only one cluster to each condition prevents separation of treatment and cluster effects in a behavioral-activation study of older adults.
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Statistical rigorReporting transparencyNutrition & aging
Author affiliations & identifiers
- Yasaman Jamshidi-Naeini: Department of Epidemiology and Biostatistics, Indiana University School of Public Health- Bloomington, 1025 E 7th St, PH 111, Bloomington, IN, 47405, USA.
- Lilian Golzarri-Arroyo: Department of Epidemiology and Biostatistics, Indiana University School of Public Health- Bloomington, 1025 E 7th St, PH 111, Bloomington, IN, 47405, USA.
- Abu Bakkar Siddique: Department of Epidemiology and Biostatistics, Indiana University School of Public Health- Bloomington, 1025 E 7th St, PH 111, Bloomington, IN, 47405, USA.
- Colby J Vorland: Department of Epidemiology and Biostatistics, Indiana University School of Public Health- Bloomington, 1025 E 7th St, PH 111, Bloomington, IN, 47405, USA.
- David B Allison: Department of Epidemiology and Biostatistics, Indiana University School of Public Health- Bloomington, 1025 E 7th St, PH 111, Bloomington, IN, 47405, USA. allison@iu.edu. · ORCID 0000-0003-3566-9399