Rounding, but not randomization method, non-normality, or correlation, affected baseline P-value distributions in randomized trials

5Citations
Citations of this article
8Readers
Mendeley users who have this article in their library.
Get full text
This PDF is freely available from an open access repository. It may not have been peer-reviewed.

Abstract

Objectives: To investigate whether comparing observed with expected P-value distributions for baseline continuous variables in randomized controlled trials (RCTs) might be limited by randomization methods, normality and correlation of variables, or calculation of P-values from rounded summary statistics. Study Design and Setting: We assessed how each factor affects differences from expected for P-value distributions and area under the curve of the cumulative distribution function (AUC-CDF) of baseline P-values in 13 RCTs and in simulations. Results: The P-value distributions and AUC-CDF for variables with possible non-normal distribution and in simulations using eight different randomization methods were consistent with the theoretical uniform distribution and AUC-CDF, respectively, although stratification and minimization produced smaller-than-expected proportions of P-values <0.10. Seventy-seven percentage of 3,813 pairwise correlations between baseline variables in the 13 individual RCTs were between −0.2 and 0.2. P-value distribution and AUC-CDF remained consistent with the uniform distribution in simulations with incrementally increasing correlation strength. The P-value distributions calculated from rounded summary statistics were not uniform, but expected distributions could be empirically generated. Conclusions: Randomization methods, non-normality, and strength of correlation of baseline variables did not have important effects on baseline P-value distribution or AUC-CDF, but baseline P-values calculated from rounded summary statistics are non-uniformly distributed.

Cite

CITATION STYLE

APA

Bolland, M. J., Gamble, G. D., Avenell, A., & Grey, A. (2019). Rounding, but not randomization method, non-normality, or correlation, affected baseline P-value distributions in randomized trials. Journal of Clinical Epidemiology, 110, 50–62. https://doi.org/10.1016/j.jclinepi.2019.03.001

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Save time finding and organizing research with Mendeley

Sign up for free