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Related Experiment Video

Updated: May 14, 2026

Inverse Probability of Treatment Weighting (Propensity Score) using the Military Health System Data Repository and National Death Index

Inverse Probability of Treatment Weighting (Propensity Score) using the Military Health System Data Repository and National Death Index

Published on: January 8, 2020

Shift in re-randomization distribution with conditional randomization test.

Olga M Kuznetsova¹, Yevgen Tymofyeyev

¹Late Development Statistics, Merck Sharp & Dohme Corp., Rahway, NJ 07065-0900, USA. olga_kuznetsova@merck.com

Pharmaceutical Statistics

|February 15, 2013

Summary

The shift in randomization distributions, previously seen in unequal allocation, also occurs with conditional randomization tests in equal allocation studies. This shift is caused by variations in allocation ratios within the conditional reference set.

Related Experiment Videos

Last Updated: May 14, 2026

Inverse Probability of Treatment Weighting (Propensity Score) using the Military Health System Data Repository and National Death Index

Inverse Probability of Treatment Weighting (Propensity Score) using the Military Health System Data Repository and National Death Index

Published on: January 8, 2020

Area of Science:

Biostatistics
Clinical Trial Design
Statistical Inference

Background:

The unconditional randomization distribution can be shifted away from 0 in unequal allocation minimization.
Previous work linked this shift to variations in allocation ratios, suggesting allocation-preserving procedures.

Purpose of the Study:

To demonstrate that the shift phenomenon extends to conditional randomization tests, even in equal allocation studies.
To identify the cause of this shift in conditional randomization tests.
To analyze the shift's behavior in different conditional randomization settings.

Main Methods:

Investigated two types of conditional randomization tests: one conditioning on treatment group totals and another for multicenter trials.
Examined variations in the conditional allocation ratio for permuted block and biased coin randomization.
Derived the shift value for specific response vectors and its expected value for independent, identically distributed random variables.

Main Results:

The shift phenomenon in randomization distributions is present in common conditional randomization tests with equal allocation.
Variations in the conditional allocation ratio among sequences in the conditional reference set are the cause of the shift.
The study derives the shift value and analyzes its asymptotic behavior for the tested methods.

Conclusions:

Conditional randomization tests, even with equal allocation, can exhibit a shift in their distributions.
Understanding the cause (allocation ratio variation) is crucial for accurate statistical inference.
The findings have implications for the design and analysis of clinical trials using randomization.