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Biomedical subjects

J B Birch

Publications and source records attributed to J B Birch.

2 recordsLinked to original sources

An improved data analysis method for interleukin 2 microassay.

Development of the interleukin 2(IL 2) microassay, coupled with the use of highly purified or recombinant factors has allowed a detailed examination of the mechanism of action of this important biological response modifier. However, probit analysis of the microassay data does not allow inherent error of the system to be approximated nor can units of activity be assessed for significance. A computer program was developed to analyze the validity of each regression line and to generate 95% confidence intervals around each line. This program employs analysis of variance, linear regression analysis and the parallel line assay to fix confidence intervals for each IL 2 unit value. The use of recombinant IL 2 as an immunomodulator in clinical settings warrants a more precise statistical method to evaluate normal fluctuations of this factor than currently in use. The development of such a method is presented here.

Biological Assay

Robust analysis of covariance.

The simple analysis of covariance situation with two groups and one concomitant variable is considered. The parameters of this model with outliers present are estimated by the methods of at least squares and M-estimation. By use of simulation, several forms of M-estimators are compared with the least squares method. In terms of their efficiencies the tests on the equality of slopes and of adjusted means in the presence of outliers are examined under the null hypothesis by studying the behavior of t-like statistics based on the least squares and M-estimates. An example illustrates the techniques discussed.

Analysis of Variance