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P Marek

Publications and source records attributed to P Marek.

48 records · Page 3Linked to original sources
PubMed1985

A FORTRAN program for the design and analysis of sequential clinical trials.

Clinical scientists are becoming increasingly aware of the need to monitor clinical trials in progress, and to validate their procedure by the use of a formal sequential design. An interactive program, written in FORTRAN 77 and called "PEST: Planning and Evaluation of Sequential Tests," is introduced. The program can be used to design trials based on the sequential probability ratio test, the triangular test, and the restricted procedure, among others. Furthermore, from the observed terminal values of the test statistics, the program will provide an analysis which includes the significance level and point and interval estimates of the parameter of interest. The computations are based on large-sample theory which encompasses many types of patient response, including binary and ordinal outcomes as well as survival times.

Clinical Trials as Topic↗
PubMed1984

Enhancement of performance for brain stimulation reward after footshock in rats.

Rats bearing electrodes in the anterior forebrain region (AF), lateral hypothalamus (LH) or dorsal raphe (DR) nucleus were trained to press lever for brain stimulation reward. Ten minutes self- stimulation in all these placements produced a lowering of pain sensitivity as assessed by the hot-plate test. Electric footshock administered on 1 s on/4 s off paradigm for 10 min prior to self-stimulation elevated lever pressing rates in AF rats and in part of LH rats, but not in DR rats. The results are discussed in terms of opiate theory of reinforcement.

Animals↗
PubMed1979

A qualitative discrepancy between censored data rank tests.

Two popular censored data rank tests were used to compare cancer incidence rates between dogs receiving bone marrow transplantation and control dogs. The logrank test gave a significance level of 0.01. In contrast, Gehan's generalized Wilcoxon test gave a significance level of 0.76. The statistics are displayed in a manner that shows how such contrasting significance levels can arise. The Gehan statistic is shown to be subject to a serious criticism that does not apply to other Wilcoxon generalizations. Further insight into the data is obtained using a time-dependent logrank test and the proportional hazards regression model.

Animals↗