A practical approach to computing power for generalized linear models with nominal, count, or ordinal responses
Abstract
Data analysts facing study design questions on a regular basis could derive substantial benefit from a straightforward and unified approach to power calculations for generalized linear models. Many current proposals for dealing with binary, ordinal, or count outcomes are conceptually or computationally demanding, limited in terms of accommodating covariates, and/or have not been extensively assessed for accuracy assuming moderate sample sizes. Here, we present a simple method for estimating conditional power that requires only standard software for fitting the desired generalized linear model for a non‐continuous outcome. The model is fit to an appropriate expanded data set using easily calculated weights that represent response probabilities given the assumed values of the parameters. The variance–covariance matrix resulting from this fit is then used in conjunction with an established non‐central chi square approximation to the distribution of the Wald statistic. Alternatively, the model can be re‐fit under the null hypothesis to approximate power based on the likelihood ratio statistic. We provide guidelines for constructing a representative expanded data set to allow close approximation of unconditional power based on the assumed joint distribution of the covariates. Relative to prior proposals, the approach proves particularly flexible for handling one or more continuous covariates without any need for discretizing. We illustrate the method for a variety of outcome types and covariate patterns, using simulations to demonstrate its accuracy for realistic sample sizes. Copyright © 2006 John Wiley & Sons, Ltd.
Integrity 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?
More complex experimental designs can be addressed using the method of reference 95.
“More complex experimental designs can be addressed using the method of95.”
From scPower accelerates and optimizes the design of multi-sample single cell transcriptomic studies (2021) · cites this paper as [95]
Cites
(2005) · Springer eBooks · doi:10.1007/0-387-27255-0_9 · Cited by 20,333 · see citing works
Statistical Methods for Rates and Proportions
Fleiss, J. L., Levin, B., & Paik, M. C. (2003) · Wiley Series in Probability and Statistics · doi:10.1002/0471445428 · Cited by 18,646 · see citing works
McCullagh, P., & Nelder, J. A. (1989) · doi:10.1007/978-1-4899-3242-6 · Cited by 16,836 · see citing works
Wald, A. (1943) · Transactions of the American Mathematical Society · doi:10.1090/s0002-9947-1943-0012401-3 · Cited by 2,522 · see citing works
Statistical Estimates and Transformed Beta-Variables.
Minton, P. D., & Blom, G. (1960) · American Mathematical Monthly · doi:10.2307/2308690 · Cited by 1,183 · see citing works
Sample size and multiple regression analysis.
Maxwell, S. E. (2000) · Psychological Methods · doi:10.1037/1082-989x.5.4.434 · Cited by 457 · see citing works
Sample size calculations for ordered categorical data
Whitehead, J. (1993) · Statistics in Medicine · doi:10.1002/sim.4780122404 · Cited by 297 · see citing works
Kendall's advanced theory of statistics. Vol.2A: Classical inference and the linear model
Stuart, A., Ord, J. K., & Arnold, S. F. (1999) · Cited by 243 · see citing works
Applied analysis of variance in behavioral science
Edwards, L. K. (1993) · M. Dekker eBooks · Cited by 235 · see citing works
Multiple correlation: Exact power and sample size calculations.
Gatsonis, C., & Sampson, A. R. (1989) · Psychological Bulletin · doi:10.1037/0033-2909.106.3.516 · Cited by 224 · see citing works
Sample Size for Logistic Regression with Small Response Probability
Whittemore, A. S. (1981) · Journal of the American Statistical Association · doi:10.1080/01621459.1981.10477597 · Cited by 159 · see citing works
Power/Sample Size Calculations for Generalized Linear Models
Self, S. G., & Mauritsen, R. H. (1988) · Biometrics · doi:10.2307/2531897 · Cited by 150 · see citing works
Power Calculations for Likelihood Ratio Tests in Generalized Linear Models
Self, S. G., Mauritsen, R. H., & Ohara, J. (1992) · Biometrics · doi:10.2307/2532736 · Cited by 123 · see citing works
On the Use of Wald's Test in Exponential Families
Væth, M., & Væth, M. (1985) · International Statistical Review · doi:10.2307/1402935 · Cited by 82 · see citing works
Unified power analysis for t-tests through multivariate hypotheses.
OʼBrien, R. G., & Muller, K. E. (1993) · Cited by 72 · see citing works
On Power and Sample Size Calculations for Likelihood Ratio Tests in Generalized Linear Models
Shieh, G. (2000) · Biometrics · doi:10.1111/j.0006-341x.2000.01192.x · Cited by 66 · see citing works
A Tour of UnifyPow: A SAS Module/Macro for Sample-Size Analysis
OʼBrien, R. G. (1998) · Cited by 48 · see citing works
Væth, M., & Skovlund, E. (2004) · Statistics in Medicine · doi:10.1002/sim.1753 · Cited by 48 · see citing works
Adjusting power for a baseline covariate in linear models
Glueck, D. H., & Muller, K. E. (2003) · Statistics in Medicine · doi:10.1002/sim.1341 · Cited by 39 · see citing works
Sample size calculations for logistic and Poisson regression models
Shieh, G. (2001) · Biometrika · doi:10.1093/biomet/88.4.1193 · Cited by 37 · see citing works
On power and sample size calculations for Wald tests in generalized linear models
Shieh, G. (2003) · Journal of Statistical Planning and Inference · doi:10.1016/j.jspi.2003.09.017 · Cited by 28 · see citing works
Sample size calculations for comparative clinical trials with over-dispersed Poisson process data
Matsui, S. (2004) · Statistics in Medicine · doi:10.1002/sim.2011 · Cited by 28 · see citing works
A comparison of two approaches for power and sample size calculations in logistic regression models
Shieh, G. (2000) · Communications in Statistics - Simulation and Computation · doi:10.1080/03610910008813639 · Cited by 20 · see citing works
Noncentral Convergence of Wald's Large-Sample Test Statistic in Exponential Families
Stroud, T. W. F. (1973) · The Annals of Statistics · doi:10.1214/aos/1193342393 · Cited by 6 · see citing works
Flagged first, then by citations
1 of the 26 references couldn’t be matched to a known paper.
Cited by
Sorted by citations
Statistical power analyses using G∗Power 3.1: tests for correlation and regression analyses
Faul, F., Erdfelder, E., Buchner, A., & Lang, A.-G. (2009) · Behavior Research Methods · doi:10.3758/brm.41.4.1149 · Cited by 37,615 · see citing works
Sample Size Planning for Statistical Power and Accuracy in Parameter Estimation
Maxwell, S. E., Kelley, K., & Rausch, J. R. (2008) · Annual Review of Psychology · doi:10.1146/annurev.psych.59.103006.093735 · Cited by 542 · see citing works
scPower accelerates and optimizes the design of multi-sample single cell transcriptomic studies
Schmid, K. T., Höllbacher, B., Cruceanu, C., Böttcher, A., Lickert, H., Binder, E. B., Theis, F. J., & Heinig, M. (2021) · Nature Communications · doi:10.1038/s41467-021-26779-7 · Cited by 108 · see citing works
Sample size calculation for comparing two negative binomial rates
Zhu, H., & Lakkis, H. (2014) · Statistics in Medicine · doi:10.1002/sim.5947 · Cited by 97 · see citing works
Sample size calculations for evaluating mediation
Vittinghoff, E., Sen, Ś., & McCulloch, C. E. (2008) · Statistics in Medicine · doi:10.1002/sim.3491 · Cited by 86 · see citing works
Lyles, R. H., & Lin, J. (2010) · Statistics in Medicine · doi:10.1002/sim.3971 · Cited by 80 · see citing works
Self-citationPower Calculations for ZIP and ZINB Models
Williamson, J. M., Lin, H., Lyles, R. H., & Hightower, A. W. (2021) · Journal of Data Science · doi:10.6339/jds.2007.05(4).360 · Cited by 31 · see citing works
Self-citationEarly Thoracic Sympathetic Block Improves the Treatment Effect for Upper Extremity Neuropathic Pain
Yoo, H. S., Nahm, F. S., Lee, P. B., & Lee, C. J. (2011) · Anesthesia & Analgesia · doi:10.1213/ane.0b013e3182274803 · Cited by 28 · see citing works
Does Being Verified Make You More Credible?
Vaidya, T., Votipka, D., Mazurek, M. L., & Sherr, M. (2019) · CHI Conference on Human Factors in Computing Systems · doi:10.1145/3290605.3300755 · Cited by 28 · see citing works
Power estimation using simulations for air pollution time-series studies
Winquist, A. G., Klein, M., Tolbert, P. E., & Sarnat, S. E. (2012) · Environmental Health · doi:10.1186/1476-069x-11-68 · Cited by 26 · see citing works
Determining Sample Size in Logistic Regression with G-Power
Yenipınar, A., Koç, Ş., Çanga, D., & Kaya, F. (2019) · DergiPark (Istanbul University) · Cited by 24 · see citing works
Sample size issues in time series regressions of counts on environmental exposures
Armstrong, B., Gasparrini, A., Tobı́as, A., & Sera, F. (2020) · BMC Medical Research Methodology · doi:10.1186/s12874-019-0894-6 · Cited by 23 · see citing works
Exemplary data set sample size calculation for Wilcoxon–Mann–Whitney tests
Divine, G., Kapke, A., Havstad, S. L., & Joseph, C. L. M. (2009) · Statistics in Medicine · doi:10.1002/sim.3770 · Cited by 22 · see citing works
The relationship between sustained inattentional blindness and working memory capacity
Beanland, V., & Chan, E. (2016) · Attention Perception & Psychophysics · doi:10.3758/s13414-015-1027-x · Cited by 21 · see citing works
Bendersky, C., & Brockner, J. (2020) · Journal of Organizational Behavior · doi:10.1002/job.2441 · Cited by 21 · see citing works
Sample Size for Joint Testing of Indirect Effects
Vittinghoff, E., & Neilands, T. B. (2014) · Prevention Science · doi:10.1007/s11121-014-0528-5 · Cited by 19 · see citing works
Curtailment as a successful method for reducing bat mortality at a southern Australian wind farm
Bennett, E. M., Florent, S. N., Venosta, M., Gibson, M. S., Jackson, A., & Stark, E. (2022) · Austral Ecology · doi:10.1111/aec.13220 · Cited by 16 · see citing works
Larivière, C., Rabhi, K., Preuss, R. A., Coutu, M., Roy, N., & Henry, S. M. (2022) · PLoS ONE · doi:10.1371/journal.pone.0265970 · Cited by 13 · see citing works
Power and sample size calculations for Poisson and zero-inflated Poisson regression models
Channouf, N., Frédette, M., & MacGibbon, B. (2013) · Computational Statistics & Data Analysis · doi:10.1016/j.csda.2013.09.029 · Cited by 13 · see citing works
Holland, M. L., Yoo, B., Kitzman, H. J., Chaudron, L. H., Szilagyi, P. G., & Temkin‐Greener, H. (2010) · Maternal and Child Health Journal · doi:10.1007/s10995-010-0719-z · Cited by 13 · see citing works
Sample Size Determination for Logistic Regression: A Simulation Study
Bush, S. (2014) · Communications in Statistics - Simulation and Computation · doi:10.1080/03610918.2013.777458 · Cited by 13 · see citing works
Hassouna, A. (2023) · Springer eBooks · doi:10.1007/978-3-031-20758-7_4 · Cited by 13 · see citing works
Goedhart, P. W., van der Voet, H., Baldacchino, F., & Arpaia, S. (2014) · Ecology and Evolution · doi:10.1002/ece3.1019 · Cited by 11 · see citing works
Luo, S., Xie, J., Chen, J., Li, H., & Zhang, S. (2024) · Frontiers in Psychology · doi:10.3389/fpsyg.2024.1411055 · Cited by 10 · see citing works
Sample size calculations for comparing two groups of count data
Wang, L., & Fan, C. (2018) · Journal of Biopharmaceutical Statistics · doi:10.1080/10543406.2018.1489409 · Cited by 10 · see citing works
Examples of Computing Power for Zero-Inflated and Overdispersed Count Data
Doyle, S. R. (2009) · Journal of Modern Applied Statistical Methods · doi:10.22237/jmasm/1257033720 · Cited by 8 · see citing works
Li, C.-I., & Shyr, Y. (2016) · Statistical Applications in Genetics and Molecular Biology · doi:10.1515/sagmb-2016-0008 · Cited by 7 · see citing works
An Improved Sample Size Calculation Method for Score Tests in Generalized Linear Models
Tang, Y., Zhu, L., & Gu, J. (2020) · Statistics in Biopharmaceutical Research · doi:10.1080/19466315.2020.1756398 · Cited by 7 · see citing works
Lin, H., & Williamson, J. M. (2014) · Journal of Biopharmaceutical Statistics · doi:10.1080/10543406.2014.971163 · Cited by 7 · see citing works
Self-citationBlinded sample size reestimation for negative binomial regression with baseline adjustment
Zapf, A., Asendorf, T., Anten, C., Mütze, T., & Friede, T. (2020) · Statistics in Medicine · doi:10.1002/sim.8525 · Cited by 5 · see citing works
Power and sample size calculations for interval‐censored survival analysis
Kim, H., Williamson, J. M., & Lin, H. (2015) · Statistics in Medicine · doi:10.1002/sim.6832 · Cited by 5 · see citing works
Self-citationFreire, I. V., Ribeiro, Í. J. S., Casotti, C. A., Andrade, D. M. B., Bezerra, D. D., Teixeira, J. R. B., Barbosa, A. A. L., Campos, L. C. G., & Pereira, R. (2025) · High Blood Pressure & Cardiovascular Prevention · doi:10.1007/s40292-025-00725-w · Cited by 4 · see citing works
Power and Sample Size Calculations for Models from Unknown Distributions
Mahnken, J. D. (2009) · Statistics in Biopharmaceutical Research · doi:10.1198/sbr.2009.0033 · Cited by 4 · see citing works
Optimal designs for testing the efficacy of heterogeneous experimental groups
Antognini, A. B., Frieri, R., Novelli, M., & Zagoraiou, M. (2021) · Electronic Journal of Statistics · doi:10.1214/21-ejs1864 · Cited by 4 · see citing works
Trajectory of Journal Article Publications for Counselor Educators at Comprehensive Universities
Hatchett, G. T. (2022) · The Professional Counselor · doi:10.15241/gth.12.2.138 · Cited by 4 · see citing works
Unpredictable needs are associated with lower expectations of repayment
Beltrán, D. G., Mercado, D. L., Ayers, J. D., Horn, A. V., Alcock, J., Todd, P. M., Cronk, L., & Aktipis, A. (2023) · Current Research in Ecological and Social Psychology · doi:10.1016/j.cresp.2023.100095 · Cited by 4 · see citing works
Zhang, Z., & Sun, L. (2023) · Bioinformatics · doi:10.1093/bioinformatics/btad139 · Cited by 4 · see citing works
Solomon, M., Yon-Hernández, J. A., Ruder, S., McGurk, S. R., Tancredi, D. J., Takarae, Y., & Stahmer, A. C. (2025) · Contemporary Clinical Trials Communications · doi:10.1016/j.conctc.2025.101536 · Cited by 3 · see citing works
Selvaratnam, S., Oyet, A. J., Yi, Y., & Gadag, V. G. (2017) · Canadian Journal of Statistics · doi:10.1002/cjs.11324 · Cited by 3 · see citing works
Menon, S., Massaro, J. M., Lewis, J. W., Pencina, M. J., Wang, Y., & Lavin, P. T. (2011) · Statistics in Biopharmaceutical Research · doi:10.1198/sbr.2011.10015 · Cited by 3 · see citing works
Saurine, F., Ryeland, J., Ekanayake, K. B., Maguire, G. S., & Weston, M. A. (2024) · Global Ecology and Conservation · doi:10.1016/j.gecco.2024.e03115 · Cited by 2 · see citing works
Reichert, C. S., Pienkohs, S. P., Skroch, L., Meisgeier, A., & Neff, A. (2025) · Journal of Clinical Medicine · doi:10.3390/jcm14010266 · Cited by 2 · see citing works
Larval Movement of Spotted Wing Drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae)
Ballman, E. S., & Drummond, F. A. (2019) · Journal of the Kansas Entomological Society · doi:10.2317/0022-8567-92.1.412 · Cited by 2 · see citing works
Power and sample size for GEE analysis of incomplete paired outcomes in 2 × 2 crossover trials
Tang, Y. (2021) · Pharmaceutical Statistics · doi:10.1002/pst.2112 · Cited by 2 · see citing works
An Efficient Gatekeeper Algorithm for Detecting GxE
Efird, J. T. (2010) · Cancer Informatics · doi:10.4137/cin.s4731 · Cited by 1 · see citing works
Wellek, S. (2017) · Statistics in Medicine · doi:10.1002/sim.7360 · Cited by 1 · see citing works
Tamura, R., & Liu, X. (2015) · Statistics in Biopharmaceutical Research · doi:10.1080/19466315.2015.1037965 · Cited by 1 · see citing works
Raim, A. M., Mathew, T., Sellers, K. F., Ellis, R., & Meyers, M. (2023) · Journal of Official Statistics · doi:10.2478/jos-2023-0009 · Cited by 1 · see citing works
Abdullah, M. A. A. (2014) · UTHM Institutional Repository (Universiti Tun Hussein Onn Malaysia)
Ramezani, N. (2017) · Scholarship & Creative Works - Digital UNC a service of University Libraries (University of Northern Colorado)
Statistical inference for adaptive designs in multi-center clinical trials
Selvaratnam, S. (2018) · Memorial University Research Repository (Memorial University)
Xie, J., Ke, H., Li, H., Chen, J., Luo, S., & Da-jiang, S. (2025) · Journal of Resources and Ecology · doi:10.5814/j.issn.1674-764x.2025.05.015
Robust power and sample size calculations in quasi-likelihood models: methods and practice
Yuan, S., Cochran, A. L., & Rathouz, P. J. (2026) · BMC Medical Research Methodology · doi:10.1186/s12874-026-02940-y
Gumaa, M., & Hassouna, A. (2026) · Elsevier eBooks · doi:10.1016/b978-0-443-45595-7.00009-1
Marx, T., Hubert, M., & Mariani, M. M. (2026) · Psychology and Marketing · doi:10.1002/mar.70280
- Authors
- Lyles, R. H., Lin, H., & Williamson, J. M.
- Affiliations
- Emory University (US)
- Pennsylvania State University (US)
- Centers for Disease Control and Prevention (US)
- Corresponding author
- Lyles, Robert H.
- Venue
- Statistics in Medicine
- Publisher
- Wiley
- Published
- 2006-06-30
- Volume
- 26
- Issue
- 7
- Pages
- 1632-1648
- ISSN
- 0277-6715 (ISSN-L)
- 1097-0258
- OpenAlex
- W1984684068
- Cited by
- 57
- References
- 26
- Citations by year
- 2026: 3 · 2025: 4 · 2024: 2 · 2023: 4 · 2022: 3 · 2021: 5 · 2020: 4 · 2019: 3 · 2018: 2 · 2017: 3 · 2016: 2 · 2015: 2 · 2014: 5 · 2013: 2 · 2012: 1
- FWCI
- 2.19
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Statistics in Medicine (publishedVersion)
- PubMed (publishedVersion)
- Funders
- National Institute of Environmental Health Sciences (R01ES012458)
- Topics
- Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Clinical Trials
- Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Epidemiology
- Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods and Bayesian Inference
- Keywords
- power analysis, generalized linear models, conditional power, ordinal outcomes, count outcomes, Wald statistic, likelihood ratio statistic, continuous covariates, research design
- MeSH terms
- Computer Simulation, Data Interpretation, Statistical, Humans, Linear Models, 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