On the Errors of Biological Assays with Graded Responses, and Their Graphical Derivation

Abstract

The need of short cuts is stated, and algebraic expressions for variance in biological assays are developed. It is shown that results can be estimated from number of animals used, number of concentrations, variability of the material, regression slope, and that these can be used graphically. For fixed levels of some of the variables, others can be put on axes of a chart. Specimen charts are then presented, which are nomograms of two parallel scales with a third intercept scale; for selected values of number of concentrations and log interval. Construction and use are described. Data from a vitamin assay using chicks are employed, and show graphic results for confidence limits close to computed results. Appendices discuss assay efficiency and list symbols, and 4 references to other short cuts are given.