standing.jpg (37621 bytes) Andrew R. Willan, PhD

Dalla Lana School of Public Health
University of Toronto

Senior Scientist Emeritus
Program in Child Health Evaluative Sciences
SickKids Research Institute

Professor Emeritus
Department of Clinical Epidemiology and Biostatistics
McMaster University

Mailing address:
555 University Avenue, PGCRL-11.9708
Toronto, ON M5G 1X8, Canada

Office address: 686 Bay Street, Room 11.9708
Toronto, ON M5G 0A4, Canada

Courrier address: 72 Elm Street, Room 11.9708
Toronto ON M5G 1H3, Canada

telephone: +1.416.813.2166
telefax: +1.416.813.5979
confidential telefax: +1.416.813.7584


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CHL 5225H Advanced Statistical Methods for Clinical Trials

Analysis Files Associated with Recent Publications

Recent Talks by Andy Willan


Research Interests

Sample Publications

Curriculum Vitae


NIH Biosketch

Two-page CV


Dr Willan is an academic biostatistician and clinical trial methodologist, and currently holds the positions of Senior Scientist Emeritus at SickKids Research Institute, Professor of Biostatistics in the Dalla Lana School of Public Health at the University of Toronto, and Professor Emeritus in the Department of Clinical Epidemiology and Biostatistics at McMaster University. His contributions to statistical methodology include publications in the areas of cost-effectiveness analysis, value of information methods, management trials, crossover trials, non-nested regression analysis and bivariate response models. Dr Willan has been particularly instrumental in developing the field of statistical analysis of cost-effectiveness data with twenty peer-review articles and a book, co-authored with Professor Andy Briggs, in the Wiley Statistics in Practice series, entitled Statistical Analysis of Cost-effectiveness Data. More recently Dr Willan’s research interest has focused on using value of information methods for the optimal design and analysis of clinical studies, with seventeen peer-reviewed articles and two book chapters. Dr Willan’s collaborative research has been primarily in clinical trials in obstetrics and paediatrics with numerous high profile trials published in the New England Journal of Medicine and Lancet. Previously positions held included the Head of Biometry of the Clinical Trials Program at the National Cancer Institute of Canada and the Head of Clinical Trials and Epidemiology for the Cancer Program at Sunnybrook Medical Centre in Toronto.

Research Interests

Dr Willan is currently involved in methodologic research in the areas of health economics and value of information for optimal decision making in health care research and policy.

Dr Willan's current research collaborations include projects in health economics, pediatric emergency care, surgery, breast cancer, obstetrical care, supportive cancer care and cardiac devices. 

Sample Publications

  1. Freedman SB, Williamson-UrquhartS, Farion KJ, Gouin S, Willan AR et al. Multicenter trial of a combination probiotic for children with gastroenteritis. New England Journal of Medicine 2018; 379(?):2015-2026.
  2. Roth DE, Morris S, Zlotkin SK, Gernand AD, Ahmed T, Shanta SS, Willan AR et al. Vitamin D supplementation in pregnancy and lactation and infant growth. New England Journal of Medicine 2018; 379(6):535-546.
  3. Willan AR. Accounting for treatment by center interaction in sample size determinations and the use of surrogate outcomes in the pessary for the prevention of preterm birth trial: a simulation study.
  4. BMC Trials 2016; 17(1):310.

  5. Chan KKW, Xie F, Willan AR, Gupta M, Pullenayegum E. Underestimation of variance of predicted health utilities derived from multi-attribute utility instruments the use of multiple imputation as a potential solution. Medical Decision Making 2017; 37(3):262-272. doi: 10.1177/0272989X16650181.
  6. Chen MH, Willan AR. Value of information methods for assessing a new diagnostic test. Statistics in Medicine 2014; 33(11):1801-1815.
  7. Abrahamyan L, Willan AR, Beyene J, Mclimont M, Blanchette V, Feldman BM. Using value of information methods when the disease is rare and the treatment is expensive – The example of hemophilia A. Journal of General Internal Medicine 2014; 29(3):767-773.
  8. Chan KKW, Willan AR, Gupta M, Pullenayegum E. Underestimation of Uncertainties in Health Utilities derived from Mapping Algorithms involving Health Related Quality of Life Measures: Statistical Explanations and Potential Remedies. Medical Decision Making 2014; 34(7):863-872.

  9. Willan AR. Bayesian decision theory and the design and analysis of randomized clinical trials. In: van Montfort K, Oud J, and Ghidey W. (Eds.) Developments in Statistical Evaluation of Clinical Trials. Springer Berlin Heidelberg, 2014. (ISBN 978-3-642-55345-5)
  10. Willan AR. Bayesian methods for the design, analysis and interpretation of clinical studies. In: Berger VW, Zhang X. (Eds.) Important Considerations for Clinical Trial Methodologies. Future Medicine London, 2013. (eISBN 978-1-909453-31-9)
  11. Chen MH, Willan AR. Determining optimal sample sizes for multistage adaptive randomized clinical trials from an industry perspective using value of information methods. Clinical Trials 2013; 10(1):54–62.

  12. Hossain A, Willan AR, Beyene J. A flexible nonparametric approach to find candidate genes associated to disease in microarray experiments. Journal of Bioinformatics and Computational Biology 2013; 11(2):1250021 (19 pages).

  13. Barrett JFR, Hannah ME, Hutton EK, Willan AR et al. A randomized trial of planned cesarean or vaginal delivery for twin pregnancy. New England Journal of Medicine 2013; 369(14):1295-1305.

  14. Eckermann S, Willan AR. Optimal global VOI trials: better aligning manufacturer and decision maker interests and enabling feasible risk sharing. PharmacoEconomics 2013; 31(5):393-401.

  15. Hossain A, Willan AR, Beyene J. An improved method on Wilcoxon rank sum test for gene selection from microarray experiments. Communications in Statistics 2013; 42(7):1563-1577.

  16. Willan AR, Goeree R, Boutis K. Value of Information methods for planning and analyzing clinical studies optimize decision making and research planning. Journal of Clinical Epidemiology 2012; 65(8):870-876. (online)

  17. Willan AR, Eckermann S. Accounting for between-study variation in incremental net benefit in value of information methodology. Health Economics 2012; 21(10):1183–1195.

  18. Willan AR, Eckermann S. Value of information and pricing new health care interventions. PharmacoEconomics 2012; 30(6):447-459.

  19. Pullenayegum EM, Willan AR. Marginal models for censored longitudinal cost data: appropriate working variance matrices in inverse-probability-weighted GEEs can improve precision. The International Journal of Biostatistics 2011; 7(1), Article 14. (online)

  20. Willan AR. Sample size determination for cost-effectiveness trials. PharmacoEconomics 2011; 29(11):933-949.

  21. Eckermann S, Willan AR. Presenting and summarizing cost and effect evidence to best inform inference and societal decision making when comparing multiple strategies. PharmacoEconomics 2011; 29(7):563-577.

  22. Eckermann S, Coory M, Willan AR. Consistently estimating risk difference when translating evidence to jurisdiction of interest. PharmacoEconomics 2011; 29(2):87-96.

  23. Eckermann S, Karnon J, Willan AR. The value of information: Best informing research design and prioritization using current methods. PharmacoEconomics 2010; 28(9):699-709.

  24. Willan AR, Eckermann S. Optimal clinical trial design using value of information methods with imperfect implementation. Health Economics 2010; 19:549-561.

  25. Hossain A, Beyene J, Willan AR, Hu P. Approximate Likelihood ratio test for detecting differential expression in microarray data. Computational Statistics and Data Analysis 2009; 53(10):3685-3695.

  26. Eckermann S, Coory M, Willan AR. Indirect comparison: relative risk fallacies and odds solution. Journal of Clinical Epidemiology 2009; 62:1031-1036.

  27. Eckermann S, Willan AR. Globally optimal trial design for local decision making. Health Economics 2009; 18:203-216.

  28. Willan AR. Optimal sample size determinations from an industry perspective based on the expected value of information. Clinical Trials 2008; 5:587-594.

  29. Willan AR, Kowgier ME. Determining optimal sample sizes for multi-stage randomized clinical trials using value of information methods. Clinical Trials 2008; 5:289-300.

  30. Eckermann S, Willan AR. The option value of delay in health technology assessment. Medical Decision Making, 2008; 28:300-305.

  31. Eckermann S, Briggs A, Willan AR. Health technology assessment in the cost-disutility plane. Medical Decision Making 2008; 28:172-181.

  32. Willan AR, Kowgier ME. Cost-effectiveness analysis of a multinational RCT with a binary measure of effectiveness and an interacting covariate . Health Economics 2008; 17:777-791.

  33. Eckermann S, Willan AR. Time and EVSI wait for no patient. Value in Health 2008; 11:522-526.

  34. Murphy KE, Hannah ME, Willan AR et al. Multiple courses of antenatal corticosteroids for preterm birth study (MACS): a randomised controlled trial. Lancet 2008; 372:2143-2151

  35. Hodnett ED, Sremler R, Willan AR, et al. Effect on birth outcomes of a formalised approach to care in hospital labour assessment units: international, randomised controlled trial. BMJ 2008; 337: a1021.

  36. Hossain A, Willan AR. Approximate MLEs of the parameters of location-scale models under type II censoring. Statistics 2007; 41(5):385-394.

  37. Willan AR. Clinical decision making and the expected value of information. Clinical Trials 2007; 4:279-285.

  38. Pullenayegum EM, Willan AR. Semi-parametric regression models for cost-effectiveness analysis: improving the efficiency of estimation from censored data. Statistics in Medicine 2007; 26:3274-3299.

  39. Eckermann S, Willan AR. Expected value of information and decision making in HTA. Health Economics 2007; 16:195-209.

  40. Manca A, Willan AR. Lost in translation: accounting for between country differences in the analysis of multinational cost effectiveness data. Pharmacoeconomics 2006; 24:1101-1119.

  41. Willan AR, Briggs AH. The Statistical Analysis of Cost-effectiveness Data. Chichester UK: Wiley 2006.

  42. Willan AR. Statistical analysis of cost-effectiveness data from randomized clinical trials. Expert Rev. Phamacoeconomics Outcomes Res 2006; 6:337-346.

  43. Willan AR, Goeree, R, Pinto EM, McBurney C, Blackhouse G. Economic evaluation of rivastigmine in patients with parkinson’s disease dementia. Pharmacoeconomics 2006; 24:93-106.

  44. Pinto EM, Willan AR, O’Brien BJ. Cost-effectiveness analysis for multinational clinical trials. Statistics in Medicine 2005; 24:1965-1982.

  45. Willan AR, Pinto EM. The expected value of information and optimal clinical trial design. Statistics in Medicine 2005; 24:1791-1806. (Correction: Statistics in Medicine 2006; 25:720.)

  46. Willan AR, Pinto EM, O’Brien BJ, Kaul P, Goeree R, Lynd L, Armstrong PW. Country specific cost comparisons from multinational clinical trials using empirical Bayesian shrinkage estimation: the Canadian ASSENT-3 economic analysis. Health Economics 2005; 14: 327-338.

  47. Willan AR, Lin DY, Manca A. Regression methods for cost-effectiveness analysis with censored data. Statistics in Medicine. 2005; 24:131-145.

  48. Willan AR, Incremental net benefit in the analysis of economic data from clinical trials with application to the CADET-Hp Trial. European Journal of Gastroenterology and Hepatology 2004; 16:543-549.

  49. Willan AR, Briggs AH, Hoch JS. Regression methods for covariate adjustment and subgroup analysis for non-censored cost-effectiveness data. Health Economics 2004; 13: 461-475.

  50. Sears MR, Greene JM, Willan AR, et al. Persistence, remission and relapse of childhood asthma followed to adulthood: a longitudinal population-based cohort study. NEJM 2003; 349(15): 1414-1422.

  51. Willan AR, Chen EB, Cook RJ, Lin DY. Incremental net benefit in randomized clinical trials with qualify-adjusted survival. Statistics in Medicine 2003; 22:353-362.

  52. Willan AR, Lin DY, Cook RJ, Chen EB. Using inverse-weighting in cost-effectiveness analysis with censored data. Statistical Methods in Medical Research 2002; 11:539-551.

  53. Hoch JS, Briggs AH, Willan AR. Something old, something new, something borrowed, something blue: a framework for the marriage of health econometrics and cost-effectiveness analysis. Health Economics 2002; 11:415-430.

  54. O'Brien BJ, Gertsen K, Willan AR, Faulkner L, Is there a kink in consumers' threshold value for cost-effectiveness in health care. Health Economics 2002; 11:175-180.

  55. Sears MR, Greene JM, Willan AR, et al. The long-term relationship between breast-feeding and development of atopy and asthma in children and young adults: a longitudinal study. The Lancet 2002; 360:901-907.

  56. Willan AR. On the probability of cost-effectiveness using data from randomized clinical trials. BMC Medical Research Methodology 2001, 1:8.

  57. Willan AR, O'Brien BJ, Leyva RA. Cost-effectiveness analysis when the WTA is greater than the WTP. Statistics in Medicine 2001; 20:3251-3259.

  58. Willan AR, O'Brien BJ. Cost prediction models for the comparison of two groups. Health Economics 2001; 10:363-366.

  59. Willan AR, Analysis, sample size and power for estimating incremental net health benefit from clinical trial data. Control Clinical Trials 2001; 22:228-237.

  60. Willan AR, Lin DY. Incremental net benefit in randomized clinical trials. Statistics in Medicine 2001; 20:1563-1574.

  61. Feldman B, Wang E, Willan AR, Szalai JP. The randomized placebo-phase design for clinical trials. Journal of Clinical Epidemiology 2001; 54:550-557.

  62. Hannah ME, Hannah WJ, Hewson SH, Hodnett ED, Saigal S, Willan AR. Term Breech Trial: a multicentre international randomised controlled trial of planned caesarean section and planned vaginal birth for breech presentation at term. The Lancet 2000; 356:1375-1383.

  63. Willan AR, O'Brien BJ. Sample size and power issues in estimating incremental cost-effectiveness ratios from clinical trials data. Health Economics 1999; 8:203-211.

  64. Willan AR, O'Brien BJ, Cook DJ. Benefit-risk ratios in the assessment of the clinical evidence of a new therapy. Control Clinical Trials 1997; 18:121-130.

  65. Cook RJ, Willan AR. Design considerations in crossover trials with a single interim analysis and serial patient entry. Biometrics 1996; 52:732-739.

  66. Willan AR, O'Brien BJ. Confidence intervals for cost-effectiveness ratios: An application of Fieller's Theorem. Health Economics 1996; 5:297-305. Addendum 1999; 8:599.

  67. Willan AR, Cruess AF, Ballantyne M. Argon green vs krypton red laser photocoagulation of extrafoveal choroidal Neovascular Lesions: Three-year results in age-related macular generation. Canadian Journal Ophthalmology 1996; 31:11-17.

  68. Willan AR. Power function arguments in support of an alternative approach for analyzing management trials. Control Clinical Trials 1994; 15:211-219.

Last edited: 2009 January 21