Biomedical subjects

H I Patel

Publications and source records attributed to H I Patel.

4 recordsLinked to original sources

PubMed1992

Sample size for a dose-response study.

This paper deals with a method of sample size allocation for a dose-response study assuming a logistic model for the dose-response curve. The method is based on the precision with which one wishes to estimate the dose that would produce the efficacy resulting in a clinically important difference from a placebo. An example is given to illustrate the methodology. The main development of the paper is for a binary response and is suitably modified for a continuous variable.

Dose-Response Relationship, Drug↗

PubMed1991

Comparison of treatments in a combination therapy trial.

Although the min test proposed by Laska and Meisner (1) for testing superiority of a combination to each of its components is the uniformly most powerful monotone test, it is conservative in the neighborhood of origin. Considering a restricted null hypothesis, we analyze a general linear model. The p value associated with the proposed test and a confidence interval for the shortest distance between the combination therapy and component therapies are computed. Analysis of a design with two or more combinations is proposed. A numerical example is given and a problem of optimal allocation of the sample sizes and other relevant design issues are discussed.

Confidence Intervals↗

PubMed1990

A Markovian model for comparing incidences of side effects.

For clinical trials that entail observations at successive visits for the occurrence of a side effect, this paper considers a likelihood-based method to compare side effect incidence rates. The method, which employs the assumption of a Markov chain of order one for the vectors of binary responses, handles missing data due to premature withdrawals. An actual numerical example and a simulated example illustrate the technique.

Clinical Trials as Topic↗

PubMed1985

Analysis of two-period crossover design in a multicenter clinical trial.

A technique is discussed for analyzing a two-period crossover design for a multicenter trial using identical study protocols. The technique is a modification of the analysis originally proposed by Grizzle (1965, Biometrics 21, 467-480; 1974, Biometrics 30, 727) for analyzing a two-period crossover design when study is not a factor. A mixed model using the first baseline as a covariate is analyzed to increase the power of the test of significance of the treatment-by-period interaction. The baseline values are also used in a preliminary test.

Analysis of Variance↗