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Related Experiment Video

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Establishing a Competing Risk Regression Nomogram Model for Survival Data

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Published on: October 23, 2020

Graphical displays for clarifying how allocation ratio affects total sample size for the two sample logrank test.

Benjamin R Saville¹, Yong S Kim, Gary G Koch

¹Department of Biostatistics, Vanderbilt University School of Medicine, Nashville, TN 37232-2158, USA. b.saville@vanderbilt.edu

Pharmaceutical Statistics

|January 16, 2010

Summary

Unequal patient allocation in clinical trials impacts the power of the two sample logrank test. Graphical tools help determine the necessary sample size adjustments for these unbalanced study designs.

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Area of Science:

Biostatistics
Clinical Trial Design

Background:

The power of the two sample logrank test is sensitive to patient allocation ratios between treatment groups.
Unequal allocation may be necessary for data collection needs or patient acceptability of treatments.

Purpose of the Study:

To provide graphical tools for assessing sample size adjustments in unbalanced two-sample logrank test designs.
To illustrate the impact of allocation ratios on study power and required sample size.

Main Methods:

Development of graphical displays showing the sample size adjustment factor.
Analysis considering various survival rates, treatment hazard ratios, and allocation ratios.

Main Results:

The graphical displays effectively illustrate the relationship between allocation ratios and sample size requirements.
These tools quantify the cost of unbalanced designs compared to balanced ones.

Conclusions:

Graphical summaries are valuable for investigators planning sample sizes for unequal allocation in two-sample logrank tests.
These tools aid in optimizing study design under resource constraints or specific trial objectives.