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Journal ArticleDOI

A comparison between two treatments in a clinical trial with an ethical allocation design

23 Aug 2017-Journal of Statistical Computation and Simulation (Taylor & Francis)-Vol. 87, Iss: 17, pp 3377-3397

AbstractThe present article compares two treatments, say A and B, in the context of a clinical trial. Let X and Y be, respectively, the responses corresponding to A and B which have some continuous distributions. Here, the comparison is done through the parameter θ=P(X<Y) which is a very common functional in the context of reliability theory and survival analysis. We consider a two-stage data-dependent adaptive allocation design where the observations on X and Y are collected sequentially in two stages. We use the Mann–Whitney–Wilcoxon (MWW) statistic to provide a statistical comparison by a nonparametric approach. Various asymptotic results related to the proposed procedure are studied. The proposed procedure is also compared with the usual single-stage equal allocation design through statistical and clinical performances of the respective allocation procedures. more

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Journal ArticleDOI
TL;DR: A flexible method of extending a study based on conditional power, where the significance of the treatment difference at the planned end is used to determine the number of additional observations needed and the critical value necessary after accruing those additional observations.
Abstract: We propose a flexible method of extending a study based on conditional power. The possibility for extension when the p value at the planned end is small but not statistically significant is built in to the design of the study. The significance of the treatment difference at the planned end is used to determine the number of additional observations needed and the critical value necessary for use after accruing those additional observations. It may therefore be thought of as a two-stage procedure. Even though the observed treatment difference at stage 1 is used to make decisions, the Type I error rate is protected.

239 citations

Journal ArticleDOI
Abstract: The present article provides a statistical inference on comparative performances of two treatments in a clinical trial under a two-stage adaptive allocation design Suppose a fixed number (2m+n, say) of subjects are available for treatment by any of the two competing treatments, say, A and B for a particular ailment As per the proposed allocation design, 2m incoming subjects are randomised equally between A and B at the first stage Then, at the second stage, the remaining n subjects are exclusively assigned to the treatment which has higher observed median response evaluated in the first stage Under such an ethical allocation design we decide on the better treatment through an asymptotically distribution-free test procedure The related asymptotic results are also studied

1 citations

Cites methods from "A comparison between two treatments..."

  • ...Using this design Bandyopadhyay and Das (2008, 2017) have derived some methods based on Mann–Whitney U-statistic for selecting the better treatment....


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Book ChapterDOI
Abstract: Let X 1 …, X n be n independent random vectors, X v = , and Φ(x 1 …, x m ) a function of m(≤n) vectors . A statistic of the form , where the sum ∑″ is extended over all permutations (α1 …, α m ) of different integers, 1 α≤ (αi≤ n, is called a U-statistic. If X 1, …, X n have the same (cumulative) distribution function (d.f.) F(x), U is an unbiased estimate of the population characteristic θ(F) = f … f Φ(x 1,…, x m ) dF(x 1) … dF(x m ). θ(F) is called a regular functional of the d.f. F(x). Certain optimal properties of U-statistics as unbiased estimates of regular functionals have been established by Halmos [9] (cf. Section 4)

2,291 citations

Journal ArticleDOI

1,763 citations

01 Jan 1967
Abstract: Introduction and Coverage. Preliminaries. Elementary Theory of Rank Tests. Selected Rank Tests. Computation of Null Exact Distributions. Limiting Null Distributions. Limiting Non-Null Distributions. Asymptotic Optimality and Efficiency. Rank Estimates and Asymptotic Linearity.

1,636 citations

Journal ArticleDOI
Paul K. Whelton, Lawrence J. Appel, Jeanne Charleston, Arlene Taylor Dalcin, Craig K. Ewart, Linda P. Fried, Delores Kaidy, Michael J. Klag, Shiriki K. Kumanyika, Lyn Steffen, W. Gordon Walker, Albert Oberman, Karen Counts, Heidi Hataway, James M. Raczynski, Neil Rappaport, Roland Weinsier, Nemat O. Borhani, Edmund Bernauer, Patricia A. Borhani, Carlos de la Cruz, Andrew Ertl, Doug Heustis, Marshall Lee, Wade Lovelace, Ellen O'Connor, Liz Peel, Carolyn Sugars, James O. Taylor, Beth Walker Corkery, Denis A. Evans, Mary Ellen Keough, Martha Clare Morris, Eleanor Pistorino, Frank M. Sacks, Mary Cameron, Sheila Corrigan, Nancy King Wright, William B. Applegate, Amy Brewer, Laretha Goodwin, Stephen T. Miller, Joseph T. Murphy, Judy Randle, Jay M. Sullivan, Norman L. Lasser, David M. Batey, Lee Dolan, Sheila Hamill, Pat Kennedy, Vera I. Lasser, Lewis H. Kuller, Arlene W. Caggiula, N. Carole Milas, Monica E. Yamamoto, Thomas M. Vogt, Merwyn R. Greenlick, Jack F. Hollis, Victor J. Stevens, Jerome D. Cohen, Mildred Mattfeldt-Beman, Connie Brinkmann, Katherine Roth, Lana Shepek, Charles H. Hennekens, Julie E. Buring, Nancy R. Cook, Ellie Danielson, Kim Eberlein, David Gordon, Patricia R. Hebert, Jean MacFadyen, Sherry L. Mayrent, Bernard Rosner, Suzanne Satterfield, Heather Tosteson, Martin Van Denburgh, Jeffrey A. Cutler, Erica Brittain, Marilyn Farrand, Peter G. Kaufmann, Ed Lakatos, Eva Obarzanek, John Belcher, Andrea Dommeyer, Ivan Mills, Peggy Neibling, Margo Woods, B.J. Kremen Goldman, Elaine Blethen 
04 Mar 1992-JAMA
TL;DR: Weight reduction is the most effective of the strategies tested for reducing blood pressure in normotensive persons, and sodium reduction is also effective.
Abstract: Objective. —To test the short-term feasibility and efficacy of seven nonpharmacologic interventions in persons with high normal diastolic blood pressure. Design. —Randomized control multicenter trials. Setting. —Volunteers recruited from the community, treated and followed up at special clinics. Participants. —Of 16821 screenees, 2182 men and women, aged 30 through 54 years, with diastolic blood pressure from 80 through 89 mm Hg were selected. Of these, 50 did not return for follow-up blood pressure measurements. Interventions. —Three life-style change groups (weight reduction, sodium reduction, and stress management) were each compared with unmasked nonintervention controls over 18 months. Four nutritional supplement groups (calcium, magnesium, potassium, and fish oil) were each compared singly, in double-blind fashion, with placebo controls over 6 months. Main Outcome Measures. —Primary: change in diastolic blood pressure from baseline to final follow-up, measured by blinded observers. Secondary: changes in systolic blood pressure and intervention compliance measures. Results. —Weight reduction intervention produced weight loss of 3.9 kg (P .05). Conclusions. —Weight reduction is the most effective of the strategies tested for reducing blood pressure in normotensive persons. Sodium reduction is also effective. The long-term effects of weight reduction and sodium reduction, alone and in combination, require further evaluation. (JAMA. 1992;267:1213-1220)

694 citations

01 Jun 2001
Abstract: Preface. Notation and Abbreviations. Introduction. Discussion of a Simple Testing Problem. Theory of Permutation Tests for One-Sample Problems. Examples of Univariate Multi-Sample Problems. Theory of Permutation Tests for Multi-Sample Problems. Nonparametric Combination Methodology. Examples of Nonparametric Combination. Permutation Analysis in Factorial Designs. Permutation Testing with Missing Data. The Behrens-Fisher Permutation Problem. Permutation Testing for Repeated Measurements. Further Applications. References. Index

476 citations

"A comparison between two treatments..." refers background in this paper

  • ...The book by Pesarin [8] is also an useful addition to the literature in this connection....