Simple randomization may lead to unequal group sizes. Is that a problem?
Open accessIntegrity signals
Registry
Cites
Statistics
Claims the paper makes
Claims other papers make about this one
Each is checked against this paper’s own text: does it say what the citing paper says it does?
Randomization is less effective at balancing groups with small sample sizes.
“We also note that randomization is less effective at balancing groups with small sample sizes [46], and thus the randomization reported here is focused on piloting of procedures.”
From A Randomized Feasibility/Acceptability Trial of Acceptance and Commitment Therapy for People with HIV Who Drink at Unhealthy Levels. (2026) · cites this paper as [46]
Cites
1 retracted
An overview of randomization techniques: An unbiased assessment of outcome in clinical research
Suresh, K. (2011) · Journal of Human Reproductive Sciences · doi:10.4103/0974-1208.82352 · Cited by 1,070 · see citing works
RetractedFaul, F., Erdfelder, E., Lang, A.-G., & Buchner, A. (2007) · Behavior Research Methods · doi:10.3758/bf03193146 · Cited by 65,971 · see citing works
Cohen, J. (1992) · Psychological Bulletin · doi:10.1037//0033-2909.112.1.155 · Cited by 8,771 · see citing works
Kirkwood, B. R., & Sterne, J. A. C. (2014) · Bristol Research (University of Bristol) · Cited by 2,820 · see citing works
Issues in Outcomes Research: An Overview of Randomization Techniques for Clinical Trials
Kang, M., Ragan, B. G., & Park, J.-H. (2008) · Journal of Athletic Training · doi:10.4085/1062-6050-43.2.215 · Cited by 555 · see citing works
Treatment allocation by minimisation
Altman, D. G., & Bland, J. M. (2005) · BMJ · doi:10.1136/bmj.330.7495.843 · Cited by 550 · see citing works
Randomization in clinical trials: Conclusions and recommendations
Lachin, J. M., Matts, J. P., & Wei, L. J. (1988) · Controlled Clinical Trials · doi:10.1016/0197-2456(88)90049-9 · Cited by 272 · see citing works
Statistical properties of randomization in clinical trials
Lachin, J. M. (1988) · Controlled Clinical Trials · doi:10.1016/0197-2456(88)90045-1 · Cited by 200 · see citing works
Properties of simple randomization in clinical trials
Lachin, J. M. (1988) · Controlled Clinical Trials · doi:10.1016/0197-2456(88)90046-3 · Cited by 175 · see citing works
Patient compliance with orthodontic retainers in the postretention phase
Pratt, M. C., Kluemper, G. T., & Lindstrom, A. (2011) · American Journal of Orthodontics and Dentofacial Orthopedics · doi:10.1016/j.ajodo.2010.02.035 · Cited by 120 · see citing works
Assumptions for Statistical Inference
Hahn, G. J., & Meeker, W. Q. (1993) · The American Statistician · doi:10.1080/00031305.1993.10475924 · Cited by 75 · see citing works
A note on stratifying versus complete random assignment in clinical trials
Grizzle, J. E. (1982) · Controlled Clinical Trials · doi:10.1016/0197-2456(82)90026-5 · Cited by 67 · see citing works
Sample size in orthodontic randomized controlled trials: are numbers justified?
Koletsi, D., Pandis, N., & Fleming, P. S. (2013) · European Journal of Orthodontics · doi:10.1093/ejo/cjt005 · Cited by 31 · see citing works
Pandis, N., Polychronopoulou, A., & Eliades, T. (2011) · European Journal of Orthodontics · doi:10.1093/ejo/cjq141 · Cited by 30 · see citing works
Methodology and Application of Adaptive and Sequential Approaches in Contemporary Clinical Trials
Chen, Z., Zhao, Y., Cui, Y., & Kowalski, J. (2012) · Journal of Probability and Statistics · doi:10.1155/2012/527351 · Cited by 18 · see citing works
Pandis, N. (2016) · American Journal of Orthodontics and Dentofacial Orthopedics · doi:10.1016/j.ajodo.2016.04.007 · Cited by 2 · see citing works
Flagged first, then by citations
Cited by
Sorted by citations
Testa, B., Reid, J., Scott, M., Murison, P. J., & Bell, A. M. (2021) · Frontiers in Veterinary Science · doi:10.3389/fvets.2021.751949 · Cited by 43 · see citing works
Quetsch, L. B., Girard, E. I., & McNeil, C. B. (2020) · Children and Youth Services Review · doi:10.1016/j.childyouth.2020.104886 · Cited by 30 · see citing works
Psaros, C., Stanton, A. M., Raggio, G. A., Mosery, N., Goodman, G. R., Briggs, E. S., Williams, M., Bangsberg, D. R., Smit, J. A., & Safren, S. A. (2022) · International Journal of Behavioral Medicine · doi:10.1007/s12529-022-10071-z · Cited by 20 · see citing works
“Though simple randomization is easy to implement and reliably generates similar numbers of participants across larger groups, it can lead to unequal numbers in smaller groups [78].”
BackgroundLuo, X., & Hu, C. (2022) · Psychology in the Schools · doi:10.1002/pits.22721 · Cited by 18 · see citing works
Gurbuz, T. B., Aslan, K., Kasapoglu, I., Muzii, L., & Uncu, G. (2025) · European Journal of Obstetrics & Gynecology and Reproductive Biology · doi:10.1016/j.ejogrb.2025.113940 · Cited by 10 · see citing works
Examining the Complexities of Conducting Randomized Controlled Trials in Child Welfare Settings
Finne, J., Pedersen, E., Malmberg-Heimonen, I. E., & Tøge, A. G. (2024) · Evidence-Based Practice in Child and Adolescent Mental Health · doi:10.1080/23794925.2024.2384085 · Cited by 7 · see citing works
“In other words, simple randomization techniques may lead to unequal group sizes, especially with a small sample size, even if the procedure is carried out correctly (Shibasaki & Martins, 2018).”
Statistics in experimental studies on the human spine: Theoretical basics and review of applications
Bassani, T., & Galbusera, F. (2020) · Journal of the mechanical behavior of biomedical materials/Journal of mechanical behavior of biomedical materials · doi:10.1016/j.jmbbm.2020.103862 · Cited by 7 · see citing works
Cheng, Q., Ng, M. S. N., Chen, Y., Li, X., Liu, G., Zhang, M., & So, W. K. W. (2023) · Cancer Nursing · doi:10.1097/ncc.0000000000001209 · Cited by 5 · see citing works
Quiet Eye Training in Virtual Reality and in the Real-World
Bennett, J. W., Neumann, D. L., & Stainer, M. J. (2025) · Human Movement Science · doi:10.1016/j.humov.2025.103370 · Cited by 5 · see citing works
Ravindran, S., Yoganathan, S., Cairncross, Z. F., Dennis, C., Enders, J., Graves, L. E., Mill, C., Telner, D., & Brown, H. K. (2020) · Maternal and Child Health Journal · doi:10.1007/s10995-020-02980-w · Cited by 4 · see citing works
A randomized controlled trial investigating digital resilience training for healthcare professionals
Lau, Y., Choi, K. C., Wong, S. H., Ang, W. W., Ang, W. H. D., & Lau, S. T. (2025) · Scientific Reports · doi:10.1038/s41598-025-28028-z · Cited by 3 · see citing works
“Finally, an imbalance in the number of participants between groups at baseline can reduce the power of statistical tests, making it harder to identify a true effect of the intervention 69 .”
Which vehicle type is more responsive to traffic information provided on local roads?
Chang, J. S., Jeong, S., & Yang, W. (2025) · European Transport Research Review · doi:10.1186/s12544-025-00716-x · Cited by 2 · see citing works
Woolf-King, S. E., Dalton, M. R., Firkey, M., Sheinfil, A., Bucci, V., Estrada, B., Ramos, J., Hahn, J. A., Bricker, J., Gump, B., et al. (2026) · AIDS and Behavior · doi:10.1007/s10461-025-04990-7 · Cited by 1 · see citing works
“We also note that randomization is less effective at balancing groups with small sample sizes [46], and thus the randomization reported here is focused on piloting of procedures.”
Mariana, N., Gayatri, A., Widyahening, I. S., Bela, B., Soedarsono, S., Maemunah, I., Rosamarlina, R., Setiawaty, V., Myneedu, V. P., Nelwan, E. J., et al. (2025) · PLoS ONE · doi:10.1371/journal.pone.0336210 · Cited by 1 · see citing works
“In general, the baseline characteristics of patients showed no significant difference between groups [27].”
Pinto, S. T. P., Oliveira, C. R. D. M., Tanomaru‐Filho, M., & Reis, J. M. D. S. N. (2026) · PLoS ONE · doi:10.1371/journal.pone.0339002 · Cited by 1 · see citing works
“Then, the roots were stored in artificial saliva for 7 days [4,24,25].”
Wang, L., Yang, M., Khan, S., Chaudhary, M., Yang, S., Wu, F., & Zhang, L. (2026) · Arthroscopy The Journal of Arthroscopic and Related Surgery · doi:10.1002/arj.70079 · Cited by 1 · see citing works
Liu, M., Yeh, H., Kuan, A. S., Tsai, S., Liou, Y., Walsh, V., & Lau, C. I. (2020) · Journal of Geriatric Psychiatry and Neurology · doi:10.1177/0891988720915524
“Having imbalanced groups reduces the power to detect an effect of the intervention if one exists.(55) Subsequent study should include a larger sample size or use block randomization method to increase the statistical power and to reduce the chances of having imbalanced groups, respectively.”
MethodLin, L., Chi, H., Chiu, N., Huang, C.-Y., Wang, J., & Huang, D. T. (2023) · Journal of Microbiology Immunology and Infection · doi:10.1016/j.jmii.2023.09.001
Tseng, C.-C., Lau, C. I., Chou, Y.-H., Yang, K., Cheng, C., Hu, L., Li, C., Tsai, C.-F., & Liu, M. (2025) · Behavioural Brain Research · doi:10.1016/j.bbr.2025.115963
Enhancing postural health in music students: results of 6-week postural intervention program
Marko, M., & Adamčák, Š. (2026) · Physiotherapy Quarterly · doi:10.5114/pq/213796
“Randomisation was not employed due to the small sample size ( n = 16) [25] and scheduling constraints; however, the participants were carefully matched based on age and year of study to ensure pre-intervention equivalence between groups.”
Curi, A. C. C., Ferreira, A. P. A., Nogueira, L. A. C., Filho, N. M., & Ferreira, A. D. S. (2026) · International journal of osteopathic medicine · doi:10.1016/j.ijosm.2026.100858
Cincioğlu, G., & Soslu, R. (2026) · International Journal of Sports Science & Coaching · doi:10.1177/17479541261487088
Hosseini, S. E., Amirpour, M., & Javadi, M. (2026) · Preventive Care In Nursing and Midwifery Journal · doi:10.66224/pcnm.16.2.4
- Authors
- Shibasaki, W. M., & Martins, R. P.
- Affiliations
- Universidade Estadual Paulista (Unesp) (BR)
- Venue
- American Journal of Orthodontics and Dentofacial Orthopedics
- Publisher
- Elsevier BV
- Published
- 2018-10
- Volume
- 154
- Issue
- 4
- Pages
- 600-605
- ISSN
- 0889-5406 (ISSN-L)
- OpenAlex
- W2893331902
- Cited by
- 25
- References
- 16
- Citations by year
- 2026: 6 · 2025: 7 · 2024: 1 · 2023: 2 · 2022: 2 · 2021: 2 · 2020: 4 · 2019: 1
- Type
- journal article
- Language
- en
- Open access
- green
- americanae.aecid.es
- Licence
- Locations
- American Journal of Orthodontics and Dentofacial Orthopedics (publishedVersion)
- PubMed (publishedVersion)
- Americanae (AECID Library) (submittedVersion, other-oa)
- LA Referencia (Red Federada de Repositorios Institucionales de Publicaciones Científicas) (submittedVersion, other-oa)
- Topics
- Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Clinical Trials
- Health Sciences › Dentistry › Orthodontics › Orthodontics and Dentofacial Orthopedics
- Social Sciences › Decision Sciences › Management Science and Operations Research › Optimal Experimental Design Methods
- Keywords
- randomization, unequal group sizes, confounding factors, orthodontic research, experimental design
- MeSH terms
- Humans, Orthodontics, Random Allocation, Research Design, Models, Statistical, Sample Size
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
Statistics and arithmetic are recomputed, not judged.
Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.
What counts as a claim ›How we measure confidence ›How we check this ›
Are you an author, or do you see a problem with this page? Request a review
