Sample size calculation for the Wilcoxon–Mann–Whitney test adjusting for ties

Zhao, Yan; Rahardja, Dewi; Qu, Yongming

doi:10.1002/sim.2912

Cited by 56 publications

(48 citation statements)

References 16 publications

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“…17 Using sample size calculations for Wilcoxon signed-rank tests, 20 participants were required to detect a significant sum of ranks of 158 (i.e., a reduction in time to PMCD following training in 11 participants) and also to detect a difference in the median change in time to PMCD of C 2.5 min between two randomly assigned education methods, with 80% power and a type I error of 0.05. 18,19 Residents were invited to participate on an ongoing basis until the required sample size was achieved.…”

Section: Discussionmentioning

confidence: 99%

Management of simulated maternal cardiac arrest by residents: didactic teaching versus electronic learning

Hards

Davies

Salman

et al. 2012

Can J Anesth/J Can Anesth

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Section: Discussionmentioning

confidence: 99%

Management of simulated maternal cardiac arrest by residents: didactic teaching versus electronic learning

Hards

Davies

Salman

et al. 2012

Can J Anesth/J Can Anesth

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“…3 On the basis of our observational study, the required total sample size to achieve an 80% power (b¼0.2) at 5% probability of type I error (a¼0.05) for correctly detecting such difference of 5 motor score change is 18. On the basis of this calculation, this trial enrolled 40 subjects in total, 20 subjects per group.…”

Section: Statistical Analysesmentioning

confidence: 96%

Efficacy and safety of lithium carbonate treatment of chronic spinal cord injuries: a double-blind, randomized, placebo-controlled clinical trial

Yang

et al. 2011

Spinal Cord

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Study design: Lithium has attracted much attention as a neuroregenerative agent for spinal cord injury in animal models. We hypothesized that the lithium can be beneficial to patients with spinal cord injury. The safety and pharmacokinetics of lithium has been studied in our earlier phase I clinical trial, indicating its safety. This is a phase II clinical trial to evaluate its efficacy on chronic spinal cord injury patients. Objectives: The aim of this study was to investigate the efficacy of lithium on chronic spinal cord injury patients. Setting: A major spinal cord injury rehabilitation center in Beijing, China. Methods: Randomized, double-blind, placebo-controlled 6-week parallel treatment arms with lithium carbonate and with placebo. A total of 40 chronic spinal cord injury subjects were recruited. Oral lithium carbonate was titrated or placebo was simulated to maintain the serum lithium level of 0.6-1.2 mmol l À1 for 6 weeks, followed by a 6-month follow-up. The functional outcomes and the neurological classifications, as well as the safety parameters, adverse events and pharmacokinetic data were carefully collected and monitored. Results: No significant changes in the functional outcomes and the neurological classifications were found. The only significant differences were in the pain assessments using visual analog scale comparing the lithium and the placebo group. No severe adverse event was documented in the study. Conclusion: The lithium treatment did not change the neurological outcomes of patients with chronic spinal cord injury. It is worth to investigate whether lithium is effective in the treatment of neuropathic pain in chronic spinal cord injury. Sponsorship: China Spinal Cord Injury Network Company Limited.

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“…In addition, the distribution of the EDSS at the last visit in the two arms of the trial can be calculated using the transition matrices. Based on this distribution, analytical sample size calculations for the Wilcoxon test under a proportional odds model have been derived, [24] and sample size calculations for the Wilcoxon test under non-proportional odds assumptions have also been derived [28]. In addition, sample size calculations for a Wilcoxon test using the distribution of EDSS values are available in standard software via simulation.…”

Section: Discussionmentioning

confidence: 99%

Improving power to detect disease progression in multiple sclerosis through alternative analysis strategies

2011

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In patients with multiple sclerosis, investigation of a treatment effect on disease progression in clinical trials and observational studies often uses sustained progression on the expanded disability status scale (EDSS) as an outcome. It is not clear whether this outcome is the most powerful to detect a treatment effect on clinical disease progression. Assessment of EDSS modeling choice on the detection of treatment effect was of interest. This assessment was separately conducted under three potential treatment effects: treatment reducing the chance of higher future EDSS, treatment increasing the chance of lower future EDSS, and treatment leading to both effects. To assess the effect of modeling choice, nine modeling strategies were applied to the data to determine the most powerful approach. EDSS measurements were simulated at 6 month intervals for 24 months. Each patient's initial EDSS value ranged between 0 and 3, and probabilities of transitioning from one EDSS state to another were based on the empirical probabilities of transition obtained from available clinical data. Modeling approaches based on sustained progression had less power than approaches which modeled the EDSS score directly, regardless of treatment effect. This difference was especially pronounced when the treatment effect corresponded to an increase in the probability of improvement. Sustained progression on the EDSS is a less powerful outcome measure for clinical progression than approaches based on the actual EDSS values.

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Sample size calculation for the Wilcoxon–Mann–Whitney test adjusting for ties

Cited by 56 publications

References 16 publications

Management of simulated maternal cardiac arrest by residents: didactic teaching versus electronic learning

Management of simulated maternal cardiac arrest by residents: didactic teaching versus electronic learning

Efficacy and safety of lithium carbonate treatment of chronic spinal cord injuries: a double-blind, randomized, placebo-controlled clinical trial

Improving power to detect disease progression in multiple sclerosis through alternative analysis strategies

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