Two issues in limiting dilution analysis are considered. The first concerns the experimental design: a mathematical algorithm has been developed which calculates the number of replicate culture groups, and the (mean) ...
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Two issues in limiting dilution analysis are considered. The first concerns the experimental design: a mathematical algorithm has been developed which calculates the number of replicate culture groups, and the (mean) number of cells per well to be used on the basis of the experimenter''s a priori information about the unknown frequency. The procedure guarantees useful data if the a priori interval estimate of the frequency to be determined is correct and the cells are willing to grow. The second issue concerns the statistical method to be used for estimation of the unknown frequency. Several methods (minimum chi-square, maximum likelihood and the jackknife version of the maximum likelihood method) have been evaluated with artificial data from extensive Monte Carlo experiments. all three methods were useful in the statistical analysis of data. As a result of these experiments and theoretical considerations the jackknife version of the maximum likelihood estimation procedure is proposed as the statistical procedure of choice. The next best method is the maximum likelihood procedure.
作者：
TASWELL, CNYU
SCH MED MD PHD PROGRAM NEW YORK NY 10016 USA
A statistical method was developed to test the validity of the single-hit Poisson model in limiting dilution assays used to determine immunocompetent cell frequencies. Principles of bioassay, validity tests and the di...
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A statistical method was developed to test the validity of the single-hit Poisson model in limiting dilution assays used to determine immunocompetent cell frequencies. Principles of bioassay, validity tests and the distinction between model-discrimination experiments and parameter-estimation assays are reviewed in the introduction. The new test derived and then demonstrated with previously published data is intended to be used for parameter-estimation assays based upon the single-hit Poisson model. It is a family of related .chi.2, t and F tests for deviations from O of the slopes of weighted least squares regression plots. These plots regress the logarithms of single-dose estimates fi of the frequency .vphi. on the total cell doses .lambda.i and fi on the total cell dose reciprocals 1/.lambda.i, that is, Yi = In fi on Xi = .lambda.i and Yi = fi on Xi = 1/.lambda.i. The test discriminates against alternative models with multiple-hit/target response-generation processes, a variable number (dose-dependent) of false negatives and a constant number (dose-independent) of false positives. Its purposes as a test for parameter-estimation assays is to detect deviations from the single-hit Poisson model and not to select one of these alternative models. Tests for model-discrimination experiments to select or prove an unknown alternative model are considered in light of relevant literature reviewed in the discussion.
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