THE EFFECTS OF DESIGN UPON THE ERROR OF A MICROBIOLOGICAL ASSAY FOR VITAMIN B 12
- 30 September 1951
- journal article
- research article
- Published by American Society for Microbiology in Journal of Bacteriology
- Vol. 62 (4), 433-444
- https://doi.org/10.1128/jb.62.4.433-444.1951
Abstract
The microbiological assay for vit. B12, using turbidimetric measurements of the growth of Lactobacillus leichmannii, strain ATCC4797, has been found to display considerable error. In an effort to reduce this, a 4-point assay design was used in a region where the relationship between the logarithm of the concn. of the vit. B12 and the response measured as % transmission was linear. The opt. distr. of a given total number of tubes between the standard and a set of unknowns is discussed. The error variation within a rack is exemplified and the various possibilities of exptl. designs for the arrangement of the tubes to minimize its effects are discussed. A 4 x 2 doubly confounded arrangement was selected, and its use and the calculation of the results are illustrated. Error limits (P = 0.95) of about 18% were obtained from assays using a total of 8 tubes per unknown.Keywords
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