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Small studies: strengths and limitations
Open accessAbstract
A large number of clinical research studies are conducted, including audits of patient data, observational studies, clinical trials and those based on laboratory analyses. While small studies can be published over a short time-frame, there needs to be a balance between those that can be performed quickly and those that should be based on more subjects and hence may take several years to complete. The present article provides an overview of the main considerations associated with small studies. The definition of “small” depends on the main study objective. When simply describing the characteristics of a single group of subjects, for example the prevalence of smoking, the larger the study the more reliable the results. The main results should have 95% confidence intervals (CI), and the width of these depend directly on the sample size: large studies produce narrow intervals and, therefore, more precise results. A study of 20 subjects, for example, is likely to be too small for most investigations. For example, imagine that the proportion of smokers among a particular group of 20 individuals is 25%. The associated 95% CI is 9–49. This means that the true prevalence in these subjects generally is anywhere between a low or high value, which is not a useful result. When comparing characteristics between two or more groups of subjects ( e.g. examining risk factors or treatments for disease), the size of the study depends on the magnitude of the expected effect size, which is usually quantified by a relative risk, odds ratio, absolute risk difference, hazard ratio, or difference between two means or medians. The smaller the true-effect size, the larger the study needs to be 1, 2. This is because it is more difficult to distinguish between a real effect and random variation. Consider mortality as the end-point in a …
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“Studies of intervention and control group population sample sizes (N) < 10 were excluded to reduce the likelihood of small study effects, for example over-estimation of effect size [33].”
From Estimating the Effect of Aerobic Exercise Training on Novel Lipid Biomarkers: A Systematic Review and Multivariate Meta-Analysis of Randomized Controlled Trials (2023) · cites this paper as [33]
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“This fact was confirmed in 2021 by the European Institute for Gender Equality [67], which shows only 30.7% of women on Ibex-35 companies' Board of Directors.”
From Pilot study of an online brief mindfulness-based intervention to improve the well-being of managers and reduce their stress at work. (2024) · cites this paper as [67]
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Cites
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Items 101–200 of 495
Short-Term Meditation Training Fosters Mindfulness and Emotion Regulation: A Pilot Study
Fazia, T., Bubbico, F., Iliakis, I., Salvato, G., Berzuini, G., Bruno, S., & Bernardinelli, L. (2020) · Frontiers in Psychology · doi:10.3389/fpsyg.2020.558803 · Cited by 22
“Anyway results derived from an hypothesis-generating study and so data from our study can be used to design a larger confirmatory study (Hackshaw, 2008).”
ResultLee, S. Y. (2024) · BMC Medical Research Methodology · doi:10.1186/s12874-024-02235-0 · Cited by 27
“Obtaining ethical and institutional approval is easier in small studies compared with large multicentre studies [176].”
ResultHaider, S., Fatima, F., Bakhsh, K., & Ahmed, M. (2019) · Journal of Environmental Management · doi:10.1016/j.jenvman.2019.109334 · Cited by 23
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“A balance must exist between small studies, performed quickly and cheaply, and those requiring larger participant numbers, longer time durations and higher cost implications (Hackshaw 2008).”
BackgroundDing, R., Dardas, A. Z., Wang, L., & Williams, A. (2020) · Journal of Occupational and Environmental Medicine · doi:10.1097/jom.0000000000001980 · Cited by 22
“A further limitation includes the lack of a control group in our study to compare intervention results, which may lead to misidentification of random noise in our data.(67) Lastly, our intervention study was conducted solely on university employees; further studies may need to be done to determine effectiveness of int…”
ResultCognitive Function and Sleep in Caregivers of Persons Living with Dementia
Brewster, G. S., Molinari, V., McCrae, C. S., Beckstead, J. W., D’Aoust, R., & Rowe, M. A. (2021) · Western Journal of Nursing Research · doi:10.1177/01939459211041163 · Cited by 22
“The lack of correlation between the sleep continuity and cognition variables could be due to all the caregivers having poor sleep and the study having a small sample (Hackshaw, 2008).”
BackgroundOrena, E. F., Caldiroli, D., & Cortellazzi, P. (2013) · Saudi Journal of Anaesthesia · doi:10.4103/1658-354x.115351 · Cited by 22
“However, this limit does not undermine the importance of our results, as previous authors’ experience demonstrate.[24-26] This is even more true if we consider the large ES of our results.”
Tan, J., Zhao, Z., Ma, W., Liu, Y., & Zhao, H. (2024) · International Journal of Hospitality Management · doi:10.1016/j.ijhm.2024.104014 · Cited by 30
Hu, H., Xu, Z., Zhu, Q., Liu, X., Jiang, S., & Zheng, J. (2021) · Frontiers in Immunology · doi:10.3389/fimmu.2021.669398 · Cited by 22
Kola-Bezka, M. (2023) · Energy Reports · doi:10.1016/j.egyr.2022.12.143 · Cited by 21
Substance Use, Self-Esteem, and Self-Efficacy Among Homeless and Runaway Youth in New Orleans
Maccio, E. M., & Schuler, J. (2011) · Child and Adolescent Social Work Journal · doi:10.1007/s10560-011-0249-6 · Cited by 21
Inhibition of dermatophytes by photodynamic treatment with curcumin
Brasch, J., Freitag‐Wolf, S., Beck‐Jendroschek, V., & Huber, M. (2016) · Medical Mycology · doi:10.1093/mmy/myw139 · Cited by 20
Lim, A., Harijanto, C., Vogrin, S., Guillemin, G. J., & Duque, G. (2021) · International Journal of Tryptophan Research · doi:10.1177/1178646921991119 · Cited by 24
Jackson, H., Anzures‐Cabrera, J., Taylor, K. I., Pagano, G., PASADENA Investigators, & Prasinezumab Study Group (2021) · Frontiers in Neuroscience · doi:10.3389/fnins.2021.765765 · Cited by 20
“Due to the training dataset being small (only 76 patients), the results from the standardized mean differences and odds ratios may not be reliable estimates for the whole population (Hackshaw, 2008), therefore bootstrapping was used to help combat this (Dwivedi et al., 2017).”
MethodSexual orientation and gender identity inequities in cervical cancer screening by race and ethnicity
Lin, E. Y., Śleboda, P., Rimel, B. J., Chen, J. T., Hernandez, D., & Datta, G. D. (2023) · Cancer Causes & Control · doi:10.1007/s10552-023-01771-2 · Cited by 21
“…in wide confidence intervals for all reported estimates, especially in the Black and Asian/Pacific Islander populations, which decrease the reliability and precision of our estimates and therefore should not be used to make strong conclusions but rather to design larger confirmatory studies [91].”
BackgroundA systematic literature review to evaluate the tools and methods used to measure rein tension
Dumbell, L., Lemon, C., & Williams, J. M. (2018) · Journal of Veterinary Behavior · doi:10.1016/j.jveb.2018.04.003 · Cited by 25
“Care should be taken to avoid forming false-positive assumptions from the results of studies that cannot be generalized to the wider population (Hackshaw, 2008; Holmes and Jeffcott).”
BackgroundKhong, M. L., & Tanner, J. A. (2020) · Biochemistry and Molecular Biology Education · doi:10.1002/bmb.21392 · Cited by 20
“The potential limitation of such small sample size in this study is in the interpretation of quantitative results.(40) Therefore, we chose a mixed method approach to address this limitation and found that qualitative data obtained were consistent with and valuable in supporting conclusions made from the quantitative d…”
ResultTheophanous, S., Samuel, R., Lilley, J., Henry, A., Sebag-Montefiore, D., Gilbert, A., & Appelt, A. (2022) · BMC Cancer · doi:10.1186/s12885-022-09729-4 · Cited by 18
“Any factors identified and their effect estimates may suffer from small sample bias [51].”
BackgroundLu, X., Moeini, M., Li, B., Lu, Y., Damseh, R., Pouliot, P., Thorin, É., & Lesage, F. (2019) · Frontiers in Neuroscience · doi:10.3389/fnins.2019.01261 · Cited by 19
“The major limitation of our study is the small sample size used for the analyses, which may lead to potential type I (characterized as false-positive results) and type II (characterized as falsenegative results) errors (Hackshaw, 2008).”
BackgroundMelo, J., Ribeiro, A. I., Aznar, S., Pizarro, A. I. N., & Santos, M. P. (2021) · International Journal of Environmental Research and Public Health · doi:10.3390/ijerph18126588 · Cited by 18
“This may have influenced the results, especially with regard to the probability of detecting statistical significant associations between variables [77].”
BackgroundAl-Roumi, H., & Al-Sabah, R. S. (2023) · Journal of Engineering Research · doi:10.1016/j.jer.2023.10.044 · Cited by 22
Opazo, R., Bárbara Angel, B., Márquez, C., Lera, L., dos Santos, G. R. C., Monnerat, G., & Cecilia Albala, B. (2021) · Metabolomics · doi:10.1007/s11306-021-01832-0 · Cited by 18
“Finally, it is important to mention that the limitation of a small sample size influences the data interpretation and study conclusions, which restricts the universality projection of the results (Hackshaw, 2008).”
BackgroundResultLi, B. S. Y., Chan, C. W. H., Li, M., Wong, I. K. Y., & Yu, Y. H. U. (2021) · Dementia and Geriatric Cognitive Disorders Extra · doi:10.1159/000519915 · Cited by 18
Naturally-occurring fatigue and cardiovascular response to a simple memory challenge
Mlynski, C., Wright, R. A., Agtarap, S., & Rojas, J. M. (2017) · International Journal of Psychophysiology · doi:10.1016/j.ijpsycho.2017.02.011 · Cited by 18
Lee, M., Hong, S., Cho, Y., Rhee, H., Yu, M. H., Bae, J. H., Lee, Y., Lee, B., Kang, E. S., & Soo, B. (2025) · BMC Medicine · doi:10.1186/s12916-025-04017-x · Cited by 17
“First, due to a small sample size, caution is required when interpreting its results [32].”
InfluentialLee, S., Jeon, J. Y., & Kim, H. (2019) · Epilepsy & Behavior · doi:10.1016/j.yebeh.2019.106658 · Cited by 17
Bakhshi, A. K., & Ahmed, M. M. (2021) · International Journal of Injury Control and Safety Promotion · doi:10.1080/17457300.2021.1907595 · Cited by 18
“This situation is more likely to occur for those non-significant predictors with highly non-symmetrical posterior distributions (i.e., the main portion of the posterior distribution is either positive or negative) (curious readers are referred to (Hackshaw, 2008; Sch€onbrodt & Perugini, 2013)).”
BackgroundBraccioni, F., Bottigliengo, D., Ermolao, A., Schiavon, M., Loy, M., Marchi, M. R., Gregori, D., Rea, F., & Vianello, A. (2020) · Respiratory Research · doi:10.1186/s12931-020-01535-5 · Cited by 16
Seah, M.-Y., Tham, X. C., Kamaruzaman, N. R. B., & Yobas, P. K. (2017) · Archives of Psychiatric Nursing · doi:10.1016/j.apnu.2017.11.011 · Cited by 17
“Small sample sizes can affect the accuracy of inferential statistics obtained, for instance by producing inaccurate p-values (Hackshaw, 2008).”
BackgroundHesse, D., Bonifácio, C. C., Kleverlaan, C. J., & Raggio, D. P. (2018) · Journal of Applied Oral Science · doi:10.1590/1678-7757-2018-0094 · Cited by 16
Drug survival of tumor necrosis factor α inhibitors in patients with ankylosing spondylitis in Korea
Jeong, H., Eun, Y. H., Kim, I. Y., Kim, H., Ahn, J. K., Lee, J., Koh, E., & Cha, H. (2016) · The Korean Journal of Internal Medicine · doi:10.3904/kjim.2016.042 · Cited by 16
“Due to small sample size of infliximab user, there is a possibility that the HR of infliximab about TNFi discontinuation have been overestimated [27].”
BackgroundChild Sexual Abuse: the Detrimental Impact of its Specific Features
Maciel, L. P. A. A., & Basto-Pereira, M. (2020) · Child Indicators Research · doi:10.1007/s12187-020-09730-y · Cited by 18
“According to scientific evidence (e.g. Hacksaw 2008), the main problem with small sample sizes is interpretation of confidence intervals and p-values, since they can overestimate the magnitude of an association.”
Rogers, C. R., Figueroa, R., Brooks, E., Petersen, E. M., Kennedy, C. D., Gray, D. M., Sapienza, M., & Hung, M. (2021) · PubMed Central · Cited by 15
Kin-FOG: Automatic Simulated Freezing of Gait (FOG) Assessment System for Parkinson’s Disease
Soltaninejad, S., Cheng, I., & Basu, A. (2019) · Sensors · doi:10.3390/s19102416 · Cited by 15
Karatela, S., Ward, N., & Paterson, J. E. (2019) · International Journal of Environmental Research and Public Health · doi:10.3390/ijerph16122238 · Cited by 15
“Specifically, due to the small sample size, there is a risk of Type II errors, which means that it fails to reject a null hypothesis [61].”
BackgroundBilateral Tactile Feedback-Enabled Training for Stroke Survivors Using Microsoft KinectTM
Orand, A., Aksoy, E. E., Miyasaka, H., Levy, C. W., Zhang, X., & Menon, C. (2019) · Sensors · doi:10.3390/s19163474 · Cited by 15
“As Hackshaw [89] has suggested, conducting a well-designed small study is appropriate as long as its results are interpreted carefully, because small studies suffer from reliable estimation.”
BackgroundExposure to endotoxins and respiratory health in composting facilities
Aghaei, M., Yaghmaeian, K., Hassanvand, M. S., Hedayati, M. H., Yousefian, F., Janjani, H., Nabizadeh, R., & Yunesian, M. (2020) · Ecotoxicology and Environmental Safety · doi:10.1016/j.ecoenv.2020.110907 · Cited by 15
Khodabakhshi, A., & Ahmed, M. M. (2022) · Journal of Transportation Safety & Security · doi:10.1080/19439962.2022.2048761 · Cited by 17
“…sample size, which is more likely to happen for those non-significant predictors with highly nonsymmetrical posterior distributions (i.e., the main portion of the posterior distribution is either positive or negative) (curious readers are referred to (Hackshaw, 2008; Sch€onbrodt & Perugini, 2013)).”
BackgroundGibson, S. G., Raziee, H., & Lemmens, T. (2015) · World Medical & Health Policy · doi:10.1002/wmh3.131 · Cited by 16
Weinstein, A. A., Escheik, C., Oe, B., Price, J. K., Gerber, L. H., & Younossi, Z. M. (2015) · PM&R · doi:10.1016/j.pmrj.2015.06.001 · Cited by 15
“Studies with small sample sizes can produce false-positive results or overestimate the magnitude of an association [26].”
BackgroundVolkaert, B., Verbeken, S., Debeuf, T., Michels, N., & Braet, C. (2022) · Mindfulness · doi:10.1007/s12671-022-01838-2 · Cited by 14
“Additionally, it should be acknowledged that small samples have a higher risk to over-estimate the magnitude of effects, or yield false negative results (Hackshaw, 2008).”
BackgroundIntegrating motivated goal achievement in maritime simulator training
Hjellvik, S., & Mallam, S. (2023) · WMU Journal of Maritime Affairs (JoMA) · doi:10.1007/s13437-023-00309-2 · Cited by 11
“A test’s statistical significance is not less valid with a small sample size; the implication is that the observed effect size needs to be larger because it will be harder to distinguish between a real effect and random variation (Hackshaw, 2008).”
BackgroundLin, E. Y., Śleboda, P., Rimel, B. J., & Datta, G. D. (2023) · SSM - Population Health · doi:10.1016/j.ssmph.2023.101540 · Cited by 16
“…from two different years, small sample sizes of intersecting populations and variability in the data contributed to wide confidence intervals for reported estimates, and therefore results should be used to guide future confirmatory studies instead of making strong conclusions (Hackshaw, 2008).”
ResultMucoactive agents for adults with acute lung conditions: A systematic review
Tarrant, B., Maitre, C. L., Romero, L., Steward, R., Button, B., Thompson, B. R., & Holland, A. E. (2018) · Heart & Lung · doi:10.1016/j.hrtlng.2018.09.010 · Cited by 14
“Small sample sizes, especially if underpowered, can produce false-positive results.(46) This limits our conclusions and must be taken into account when applying these results clinically.”
Effect of Neural Mobilization on Nerve-Related Neck and Arm Pain: A Randomized Controlled Trial
Basson, A., Stewart, A., Mudzi, W., & Musenge, E. (2019) · Physiotherapy Canada · doi:10.3138/ptc-2018-0056 · Cited by 16
The Decline of the Experimental Paradigm During the COVID-19 Pandemic: A Template for the Future
Ferreira, J. P., Epstein, M., & Zannad, F. M. (2020) · The American Journal of Medicine · doi:10.1016/j.amjmed.2020.08.021 · Cited by 15
“It must be emphasized, however, that underpowered and poorly conducted RCTs are equally prone to bias and spurious findings.(11) Regretfully, observational, poorquality randomized and good-quality randomized studies are allocated similar press coverage and dissemination.”
Mertens, G., Wolf, N. D., Bouwman, V., & Engelhard, I. M. (2022) · International Journal of Psychophysiology · doi:10.1016/j.ijpsycho.2022.04.011 · Cited by 16
“Small studies have the tendency to overestimate the magnitude of an association (Hackshaw, 2008), whereas larger samples provide more accurate estimates of the true association and may even indicate the absence of an association.”
BackgroundResultInfluentialCompetitive interactions and coexistence of sympatric flagship carnivores in Asia
Li, Z., Lu, J., Shi, X., Duo, L., Smith, J. L. D., & Wang, T. (2023) · Integrative Zoology · doi:10.1111/1749-4877.12724 · Cited by 13
Johnson, J., Becker, M., Kaboré, J. E. P., Dossou‐Yovo, E. R., & Saito, K. (2024) · Nutrient Cycling in Agroecosystems · doi:10.1007/s10705-024-10360-x · Cited by 13
“A larger study is needed to confirm the effect sizes on performance indicators (Hackshaw 2008) and to further investigate the interaction between water management and fertilizer application rates.”
Boone, K. B., Vane, R., & Victor, T. L. (2024) · Archives of Clinical Neuropsychology · doi:10.1093/arclin/acae079 · Cited by 15
Awuah, A., Moore, J. S., McNeil, A. J., Ruddock, M. W., Brennan, P., Mailey, J. A., McNeil, A. J., Jing, M., Finlay, D., Trucco, E., et al. (2022) · Scientific Reports · doi:10.1038/s41598-022-10491-7 · Cited by 13
Exploring the Enacted Computing Curriculum in K-12 Schools in South Asia
Anwar, T., Jimenez, A., Najeeb, A. B., Upadhyaya, B., & McGill, M. M. (2020) · ACM Conference on International Computing Education Research (ICER) · doi:10.1145/3372782.3406251 · Cited by 13
“As we embarked on this study, we were aware that this trial would not provide a sample size large enough to make generalizations about the enacted computing curriculum in these countries [19, 51].”
MethodExploring Patient Perceptions of Noninvasive Brain Stimulation: A Systematic Review
Stillianesis, G., Cavaleri, R., Tang, C. Y., & Summers, S. J. (2021) · Neuromodulation Technology at the Neural Interface · doi:10.1111/ner.13461 · Cited by 13
Torre, D. L., Dalile, B., de Loor, H., Oudenhove, L. V., & Verbeke, K. (2021) · Stress · doi:10.1080/10253890.2021.1959546 · Cited by 12
“, 2018) had only a small sample of healthy volunteers (n1⁄4 10), increasing the risk of a large standard error and a consequent imprecise estimate of the effect (Hackshaw, 2008).”
Babă, D.-F., Suciu, H., Avram, C., Gyorgy, M. D., Danilesco, A., Huma, L., & Sin, I. A. (2023) · Journal of Cardiovascular Development and Disease · doi:10.3390/jcdd10020081 · Cited by 12
Agbozo, E., Alhassan, D., & Spassov, K. B. (2019) · Communications in computer and information science · doi:10.1007/978-3-030-13283-5_7 · Cited by 12
Peng, S., Ying, A. F., Tai, B. C., & Soo, R. A. (2020) · Translational Lung Cancer Research · doi:10.21037/tlcr-20-246 · Cited by 12
Keleszade, E., Willner, T., Patterson, M., Trangmar, S. J., Kolida, S., & Costabile, A. (2020) · Journal of Functional Foods · doi:10.1016/j.jff.2020.104157 · Cited by 14
van Erck, D., Dolman, C. D., Limpens, J., Reimer, W. J. M. S. O., Henriques, J. P. S., Delewi, R., & Schoufour, J. D. (2022) · Age and Ageing · doi:10.1093/ageing/afac211 · Cited by 12
“Current evidence is based on many smaller studies or studies with strength as a secondary outcome, which requires careful interpretation [12].”
BackgroundMlynski, C., Wright, R. A., & Kelly, K. S. (2020) · Biological Psychology · doi:10.1016/j.biopsycho.2020.107867 · Cited by 14
MacKenzie, O., Goldman, J. A., Chin, M. G., Duffy, B., Martino, S., Ramsey, S. E., Jiménez, M. C., & Vanjani, R. (2021) · JAMA Network Open · doi:10.1001/jamanetworkopen.2021.33384 · Cited by 11
Zeng, Y., Ge, G., Lei, C., & Zhang, M. (2022) · Frontiers in Pharmacology · doi:10.3389/fphar.2022.759742 · Cited by 11
“In that case, the overweight of those study designs in the meta-analysis may produce false-positive results (Hackshaw, 2008).”
BackgroundWu, J., Liu, C., Xie, L., Li, X., Xiao, K., Xie, G., & Xie, F. (2022) · BMC Pulmonary Medicine · doi:10.1186/s12890-022-01963-7 · Cited by 11
“…that studies with a small number of subjects can quickly address research questions in a relatively short space of time; thus, a more efficient allocation of resources (e.g. subjects, time, financial costs) be achieved by first testing a new research hypothesis in a small number of subjects [28].”
BackgroundEffects of Prenatal Tobacco and Wood-Fuel Smoke Exposure on Birth Weight in Sri Lanka
Pathirathna, M. L., Abeywickrama, H. M., Sekijima, K., Sadakata, M., Fujiwara, N., Muramatsu, Y., Wimalasiri, K. M. S., Jayawardene, U., de Silva, D., & Dematawewa, C. M. B. (2017) · Healthcare · doi:10.3390/healthcare5040064 · Cited by 11
“Hackshaw [17] reported that adjusting for several factors can fail the sensible result or they can produce unreliable results when the sample size is small.”
BackgroundBiological measures and diagnostic tools for Gulf War Illness – A systematic review
Gean, E. G., Ayers, C. K., Winchell, K. A., Freeman, M., Press, A. M., Paynter, R. A., Kansagara, D. L., & Nugent, S. M. (2021) · Life Sciences · doi:10.1016/j.lfs.2021.119360 · Cited by 11
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CREB signaling activity correlates with differentiation and survival in medulloblastoma
Armandari, I., Zomerman, W. W., Plasschaert, S. L. A., Smit, M. J., Martini, T. E. I., Magalhães, E. S. D. C., Hogeling, S. M., Rozema-Huizinga, G. C., Lourens, H. J., Boer, T. M.-D., et al. (2021) · Scientific Reports · doi:10.1038/s41598-021-95381-0 · Cited by 12
Service Characteristics and Family Involvement in an Early Childhood System of Care
Champine, R. B., Whitson, M. L., & Kaufman, J. S. (2017) · Journal of Child and Family Studies · doi:10.1007/s10826-017-0875-5 · Cited by 11
Depressive Symptoms as a Predictor of Men’s Relationship Satisfaction
Meyer, D. D., Kemper-Damm, B., Parola, F., & Salas, J. (2018) · The Family Journal · doi:10.1177/1066480718809058 · Cited by 12
Farzi, R. (2016) · uO Research (University of Ottawa) · doi:10.20381/ruor-5717 · Cited by 11
“Hadley and Reiken (1993), for example, disagree with the strict distinction that Krashen draws between learning and acquisition.”
BackgroundXia, M., Jin, C., Cao, S., Pei, B., Wang, J., Xu, T., & Jiang, H. (2022) · Annals of Translational Medicine · doi:10.21037/atm-22-2118 · Cited by 9
“In the cases of few training samples (7,8), machine learning models generally cannot achieve good out-of-sample performance, and models trained with small samples are prone to overfitting to small samples and underfitting to the target task.”
State of the evidence on simulation-based electronic health records training: A scoping review
Nuamah, J. K., Adapa, K., & Mazur, L. M. (2022) · Health Informatics Journal · doi:10.1177/14604582221113439 · Cited by 12
“101 Further, the overall number of studies with small sample size makes it challenging to assess the impact of any intervention.”
BackgroundYang, X., Wu, H., Mehta, D., Sullivan, M. C., Wang, J., Burckart, G. J., Troutman, J. A., & Fisher, J. W. (2019) · Computational Toxicology · doi:10.1016/j.comtox.2019.03.007 · Cited by 10
Bakker, L., Småstuen, M. C., Reichelt, J. G., Gjerstad, C. L., Tønnessen, A., Weisæth, L., Herlofsen, P. H., & Grov, E. K. (2019) · BMC Psychiatry · doi:10.1186/s12888-019-2159-7 · Cited by 11
Zhang, Z., Predy, M., Kuzik, N., Hewitt, L., Hesketh, K. D., Pritchard, L., Okely, A. D., & Carson, V. (2021) · Measurement in Physical Education and Exercise Science · doi:10.1080/1091367x.2021.1941033 · Cited by 10
“Second, our small sample size may lead to higher individual variance (i.e., larger standard deviation) (Hackshaw, 2008), which may have particularly influenced the individual-level agreement (e.g., wider 95% limits of agreement) observed in the study.”
Maharani, K., Adji, T. B., Setiawan, N. A., & Hidayah, I. (2015) · International Conference on Science in Information Technology · doi:10.1109/icsitech.2015.7407798 · Cited by 10
“For preventing the risk of high spending time and high financial, sometimes it is better accomplishing research in small number first [16].”
BackgroundMethodEfficacy and safety of intraoperative cone-beam CT-guided localization of small pulmonary nodules
Kaiho, T., Suzuki, H., Hata, A., Ito, T., Tanaka, K., Sakairi, Y., Kato, H., Shiko, Y., Kawasaki, Y., & Yoshino, I. (2022) · Interactive Cardiovascular and Thoracic Surgery · doi:10.1093/icvts/ivac236 · Cited by 9
“Our findings show that attaining the primary end-point was statistically significant (within a 90% CI) [17].”
Yerzhan, A., Razbekova, M., Merenkov, Y., Khudaibergenova, M. S., Abdildin, Y. G., Sarría‐Santamera, A., & Viderman, D. (2023) · Medicina · doi:10.3390/medicina59020214 · Cited by 9
Thomas, M., Führes, H., Scheer, M., Rampp, S., Strauss, C., Schönfeld, R., & Leplow, B. (2024) · Journal of Personalized Medicine · doi:10.3390/jpm14010075 · Cited by 8
The effect of cannabidiol on the pharmacokinetics of carbamazepine in rats
Darweesh, R. S., Khamis, T. N., & El‐Elimat, T. (2020) · Naunyn-Schmiedeberg s Archives of Pharmacology · doi:10.1007/s00210-020-01878-2 · Cited by 8
“Moreover, small sample size creates limited statistical power and occasionally fails in detecting significant differences (Nayak 2010; Leppink et al. 2016), which usually resulted from the high variability between subjects in small sample size, when compared to large sample size (Hackshaw 2008).”
ResultJobst, S., Windeisen, M., Wünsch, A., Meng, M. L., & Kugler, C. (2020) · BMC Medical Education · doi:10.1186/s12909-020-02220-3 · Cited by 9
“The small sample size, although seeming acceptable for a pilot study [48], impairs statistical conclusion validity and might have produced falsepositive results [60] which are not generalizable.”
BackgroundButsang, T. C., McLuhan, A., Keown, L. A., Fung, K., & Matheson, F. I. (2023) · Health & Justice · doi:10.1186/s40352-023-00218-9 · Cited by 9
“Such designs have limited statistical power and do not allow for exploration of a temporal link between outcomes and risk factors (Hackshaw, 2008; Setia, 2016).”
BackgroundBabă, D.-F., Suciu, H., Huma, L., Avram, C., Danilesco, A., Moldovan, D.-A., Opincar, A. S., & Sin, A. I. (2023) · Journal of Cardiovascular Development and Disease · doi:10.3390/jcdd10060241 · Cited by 9
“The decreased number of subjects in the cohort may influence our results due to falsepositive scores, with the possibility of overestimating the extent of the associations [43].”
BackgroundSilago, V., Mukama, Y., Haule, A. L., Chacha, F., Igenge, J., Mushi, M. F., & Mshana, S. E. (2020) · African Health Sciences · doi:10.4314/ahs.v20i1.4 · Cited by 10
Trends of Anger and Physical Aggression in Russian Women During COVID-19 Lockdown
Klimovich-Mickael, A., Kubick, N., Milanesi, E., Dobre, M., Łazarczyk, M., Wijas, B., Sacharczuk, M., & Mickael, M. (2021) · Frontiers in Global Women s Health · doi:10.3389/fgwh.2021.698151 · Cited by 9
Halperin, L., & Falk-Kessler, J. P. (2020) · The Open Journal of Occupational Therapy · doi:10.15453/2168-6408.1659 · Cited by 9
“If findings of small sample studies reach significance with moderate to large effect size, there is evidence to explore further (Hackshaw, 2008).”
BackgroundNey, L. J., Laing, P. A. F., Steward, T., Zuj, D. V., Dymond, S., Harrison, B. J., Graham, B. M., & Felmingham, K. L. (2022) · PLoS ONE · doi:10.1371/journal.pone.0268814 · Cited by 10
Lyu, Y. R., Lee, S.-W., Kim, S. Y., Han, H.-B., Yang, W., Kim, S., Jung, I. C., Kwon, O., Kim, A., Kim, J., et al. (2022) · Evidence-based Complementary and Alternative Medicine · doi:10.1155/2022/3485757 · Cited by 12
“As a small study, there are limitations in concluding reliable and precise results, due to the problems with a large standard error, false-positive errors, and statistical analyses [35], and thus our study results can also provide only preliminary data on the efficacy of herbal medicines in obstructive airway disease.”
ResultLetter, R. T., Dwyer, D., Drinkwater, E. J., & Feros, S. A. (2022) · International Journal of Sports Physiology and Performance · doi:10.1123/ijspp.2022-0116 · Cited by 9
Sugrim, S., Liu, C., & Lindqvist, J. (2019) · Proceedings of the ACM on Interactive Mobile Wearable and Ubiquitous Technologies · doi:10.1145/3351262 · Cited by 9
“Hackshaw [25] overviews the strengths and limitations of small sample size in clinical studies.”
BackgroundLeite, C. B. S., Coelho, J. M., Ferreira‐Nunes, R., Gelfuso, G. M., Durigan, J. L. Q., Azevedo, R. B., Muehlmann, L. A., & Sousa, M. H. (2020) · Nanomedicine · doi:10.2217/nnm-2019-0317 · Cited by 9
Intra-individual variation of upper airway measurements based on computed tomography
Zhou, N., Ho, J. T. F., Klop, C., Schreurs, R., Beenen, L. F. M., Aarab, G., & de Lange, J. (2021) · PLoS ONE · doi:10.1371/journal.pone.0259739 · Cited by 9
“This variation is not expected to decrease with a larger sample size; only its estimate will be more precise [37].”
BackgroundHemanny, C., de Sena, E. P., & de Oliveira, I. R. (2021) · Journal of Clinical Pharmacy and Therapeutics · doi:10.1111/jcpt.13535 · Cited by 8
Theophanous, S., Lønne, P.-I., Choudhury, A., Berbée, M., Dekker, A. L. A. J., Dennis, K. E. B., Dewdney, A., Gambacorta, M. A., Gilbert, A., Guren, M. G., et al. (2022) · Diagnostic and Prognostic Research · doi:10.1186/s41512-022-00128-8 · Cited by 8
Yui, K., Imataka, G., & Shiohama, T. (2023) · Current Issues in Molecular Biology · doi:10.3390/cimb45110574 · Cited by 8
“According to a former clinical study, despite the small sample size (12 patients), statistically significant improvement was obtained by an intensive neuro-rehabilitation surface program with electromyography [27].”
Wang, X. J., Goh, D. Y. T., Dorajoo, S. R., & Chan, A. (2017) · Supportive Care in Cancer · doi:10.1007/s00520-017-3696-6 · Cited by 8
van der Weijden, F. N., Hesse, D., Americano, G. C. A., Soviero, V. M., & Bonifácio, C. C. (2019) · International Journal of Paediatric Dentistry · doi:10.1111/ipd.12568 · Cited by 7
Park, J. M., Chiu, C., Chen, S.-C., Lee, W., & Chen, C.-Y. (2020) · Neuropeptides · doi:10.1016/j.npep.2020.102032 · Cited by 8
Griffin-Shirley, N., Bozeman, L. A., Nguyen, T., Othuon, V., Page, A., Hahm, J., Hahm, J., & Lee, J. (2021) · Journal of Visual Impairment & Blindness · doi:10.1177/0145482x211018000 · Cited by 8
“Hackshaw (2008) opines that the principal problem with small sample studies is the interpretation of results.”
BackgroundRavanbod, H. R. (2022) · Journal of Foot and Ankle Research · doi:10.1186/s13047-022-00581-0 · Cited by 8
“Given the relatively small sample size in part of included studies and the high-risk levels, our findings should be interpreted with caution [53].”
Background
Metadata
- Authors
- Hackshaw, A.
- Affiliations
- Cancer Research UK (GB)
- Corresponding author
- Hackshaw, A.
- ORCID
- Hackshaw, A.
- Venue
- European Respiratory Journal
- Publisher
- European Respiratory Society (ERS)
- Published
- 2008-10-31
- Volume
- 32
- Issue
- 5
- Pages
- 1141-1143
- ISSN
- 0903-1936 (ISSN-L)
- 1399-3003
- OpenAlex
- W2097412619
- Cited by
- 496
- References
- 7
- Citations by year
- 2026: 29 · 2025: 36 · 2024: 37 · 2023: 56 · 2022: 57 · 2021: 86 · 2020: 51 · 2019: 38 · 2018: 24 · 2017: 20 · 2016: 20 · 2015: 17 · 2014: 9 · 2013: 5 · 2012: 5
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- European Respiratory Journal (publishedVersion)
- PubMed (publishedVersion)
- UCL Discovery (University College London) (submittedVersion)
- Topics
- Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Epidemiology
- Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Clinical Trials
- Social Sciences › Decision Sciences › Statistics, Probability and Uncertainty › Meta-analysis and systematic reviews
- Keywords
- small sample size, sample size determination, confidence intervals, statistical power, effect size, clinical research design, research limitations, prevalence estimation
- MeSH terms
- Antineoplastic Agents, Clinical Trials as Topic, Data Interpretation, Statistical, Diet Therapy, Humans, Lung Neoplasms, Research Design, Risk Factors, Smoking, Thalidomide, Time Factors, Reproducibility of Results, Weight Loss, Sample Size, Small Cell Lung Carcinoma
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