Biomedical subjects

B C Tai

Publications and source records attributed to B C Tai.

3 recordsLinked to original sources

PubMed1998

Sample size and power calculations for comparing two independent proportions in a 'negative' trial.

Statistical methods for evaluating the adequacy of sample size and power cater mainly to the testing for treatment difference in a 'positive' trial. In biomedical research, the trial can sometimes be postulated as 'negative' to demonstrate that the different treatment groups are statistically equivalent. Herein we describe a computer program to determine the adequacy of sample size and power for comparing two independent proportions in a 'negative' trial. The program is written in MicroSoft QuickBasic Version 4.5, and its executable file is suitable for use as a stand-alone program on a microcomputer.

Clinical Trials as Topic↗

PubMed1997

Comparing a sample proportion with a specified population proportion based on the mid-P method.

A common practice for determining whether a sample proportion is statistically different from a specified population proportion is using the exact probability procedure. However, it produces overly conservative confidence intervals and p-values. A stand-alone executable program is written for applying alternative approaches based on the mid-P and bootstrap methods.

Confidence Intervals↗

PubMed1995

Quantitative versus qualitative urinalysis for benzoylecgonine in clinical trials for the assessment of cocaine use.

Urinalysis of benzoylecgonine (BE) concentrations is a primary outcome measure for evaluating medications for treating cocaine addiction. Using simulated BE data from a set of simple clinical models, the advantages of quantitative versus qualitative urinalysis were evaluated, as well as the advantages of once-weekly versus thrice-weekly sampling schedules. A 60 percent reduction in cocaine use, either in daily amount or in weekly frequency, was considered clinically significant. Quantitative urinalysis can detect reductions in both amount and frequency, whereas qualitative urinalysis can detect only a decrease in frequency. For quantitative urinalysis, changes are more easily detected when urine is collected three times a week than when it is collected once a week. For qualitative urinalysis, the majority rule analysis for a thrice-weekly sampling schedule yields an artificially high estimate of the percentage of positive samples, whereas a once-weekly schedule gives a highly variable estimate.

Cocaine↗