General information

• When can a clinical trial be called ´randomized`? – Berger VW, et al. Vaccine. 2003 Jan 17;21(5-6):468-72. doi: 10.1016/s0264-410x(02)00475-9.
• Design and analysis of stratified clinical trials in the presence of bias – Hilgers RD, Manolov M, Heussen N, Rosenberger WF. Stat Methods Med Res. 2020 Jun;29(6):1715-1727. doi: 10.1177/0962280219846146. Epub 2019 May 10.
• A Better Alternative to Stratified Permuted Block Design for Subject Randomization in Clinical Trials – Zhao W. Stat Med. 2014 Dec 30;33(30):5239-48. doi: 10.1002/sim.6266. Epub 2014 Jul 14.

How to randomize

• The asymptotic maximal procedure for subject randomization in clinical trials – Zhao W, et al. Stat Methods Med Res. 2018 Jul;27(7):2142-2153. doi: 10.1177/0962280216677107. Epub 2016 Nov 16.
• A comparative study of restricted randomization procedures for multiarm trials with equal or unequal treatment allocation ratios – Ryeznik Y, Sverdlov O. Stat Med. 2018 Sep 20;37(21):3056-3077. doi: 10.1002/sim.7817. Epub 2018 Jun 4.
• Implementing unequal randomization in clinical trials with heterogeneous treatment costs – Sverdlov O, Ryeznik Y. Stat Med. 2019 Jul 20;38(16):2905-2927. doi: 10.1002/sim.8160. Epub 2019 May 3.
• ERDO – a framework to select an appropriate randomization procedure for clinical trials – Hilgers RD, Uschner D, Rosenberger WF, Heussen N. BMC Med Res Methodol. 2017 Dec 4;17(1):159. doi: 10.1186/s12874-017-0428-z.
• A Better Alternative to Stratified Permuted Block Design for Subject Randomization in Clinical Trials – Zhao W. Stat Med. 2014 Dec 30;33(30):5239-48. doi: 10.1002/sim.6266. Epub 2014 Jul 14.
• Quantitative Comparison of Randomization Designs in Sequential Clinical Trials Based on Treatment Balance and Allocation Randomness – Zhao W, et al. Pharm Stat. Jan-Feb 2012;11(1):39-48. doi: 10.1002/pst.493. Epub 2011 May 5.
• Block urn design – a new randomization algorithm for sequential trials with two or more treatments and balanced or unbalanced allocation – Zhao W, et al. Contemp Clin Trials. 2011 Nov;32(6):953-61. doi: 10.1016/j.cct.2011.08.004. Epub 2011 Aug 22.

How should I not randomize

• Do not use blocked randomization – Berger VW. Headache. 2006 Feb;46(2):343; author reply 343-5. doi: 10.1111/j.1526-4610.2006.00351_5.x.
• Characterizing permuted block randomization as a big stick procedure – Berger VW, et al. Contemp Clin Trials Commun. 2016 Jan 29;2:80-84. doi: 10.1016/j.conctc.2016.01.001. eCollection 2016 Apr 15.
• Varying the block size does not conceal the allocation – Berger VW. J Crit Care. 2006 Jun;21(2):229; author reply 229-30. doi: 10.1016/j.jcrc.2006.01.002.

How to detect selection (and other) bias

• Detecting Selection Bias in Randomized Clinical Trials – Berger VW, et al. Control Clin Trials. 1999. Aug;20(4):319-27. doi: 10.1016/s0197-2456(99)00014-8.
• Randomization in survival studies: An evaluation method that takes into account selection and chronological bias – Rückbeil MV, Hilgers RD, Heussen N. PLoS One. 2019 Jun 3;14(6):e0217946. doi: 10.1371/journal.pone.0217946. eCollection 2019.
• The impact of selection bias in randomized multi-arm parallel group clinical trials – Uschner D, Hilgers RD, Heussen N. PLoS One. 2018 Jan 31;13(1):e0192065. doi: 10.1371/journal.pone.0192065. eCollection 2018.
• Assessing the impact of selection bias on test decisions in trials with a time-to-event outcome – Rückbeil MV, Hilgers RD, Heussen N. Stat Med. 2017 Jul 30;36(17):2656-2668. doi: 10.1002/sim.7299. Epub 2017 Apr 17.
• Chronological bias in randomized clinical trials arising from different types of unobserved time trends – Tamm M, Hilgers RD. Methods Inf Med. 2014;53(6):501-10. doi: 10.3414/ME14-01-0048. Epub 2014 Nov 14.

How to avoid selection bias

• Minimizing predictability while retaining balance through the use of less restrictive randomization procedures – Berger VW, et al. Stat Med. 2003 Oct 15;22(19):3017-28. doi: 10.1002/sim.1538.
• Ensuring the comparability of comparison groups: is randomization enough? – Ensuring the comparability of comparison groups: is randomization enough? Berger VW, et al. Control Clin Trials. 2004. Control Clin Trials. 2004 Oct;25(5):515-24. doi: 10.1016/j.cct.2004.04.001.

Why shouldn’t I use permuted blocks 

• Do not use blocked randomization – Berger VW. Headache. 2006 Feb;46(2):343; author reply 343-5. doi: 10.1111/j.1526-4610.2006.00351_5.x.
• Comparing MTI randomization procedures to blocked randomization – Berger VW, et al. Stat Med. 2016 Feb 28;35(5):685-94. doi: 10.1002/sim.6637. Epub 2015 Sep 3.
• Characterizing permuted block randomization as a big stick procedure – Berger VW, et al. Contemp Clin Trials Commun. 2016 Jan 29;2:80-84. doi: 10.1016/j.conctc.2016.01.001. eCollection 2016 Apr 15.
• Block urn design – a new randomization algorithm for sequential trials with two or more treatments and balanced or unbalanced allocation – Zhao W, et al. Contemp Clin Trials. 2011 Nov;32(6):953-61. doi: 10.1016/j.cct.2011.08.004. Epub 2011 Aug 22.

Why shouldn’t I use minimization 

Why isn’t it enough to vary the block sizes for use with permuted blocks 

• Varying the block size does not conceal the allocation – Berger VW. J Crit Care. 2006 Jun;21(2):229; author reply 229-30. doi: 10.1016/j.jcrc.2006.01.002.

How should I analyze randomized trials

• Design and analysis of stratified clinical trials in the presence of bias – Hilgers RD, Manolov M, Heussen N, Rosenberger WF. Stat Methods Med Res. 2020 Jun;29(6):1715-1727. doi: 10.1177/0962280219846146. Epub 2019 May 10.
• Inference for blocked randomization under a selection bias model – Kennes LN, Rosenberger WF, Hilgers RD. Biometrics. 2015 Dec;71(4):979-84. doi: 10.1111/biom.12334. Epub 2015 Jun 22.
• Influence of selection bias on the test decision. A simulation study – Tamm M, Cramer E, Kennes LN, Heussen N. Methods Inf Med. 2012;51(2):138-43. doi: 10.3414/ME11-01-0043. Epub 2011 Nov 21.
• The impact of selection bias on test decisions in randomized clinical trials – Kennes LN, Cramer E, Hilgers RD, Heussen N. Stat Med. 2011 Sep 20;30(21):2573-81. doi: 10.1002/sim.4279. Epub 2011 Jun 30.