Summary
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1. An automatic cathetometric instrumentation that objectively interpolates and prints diffusion measurements to 0.001 mm has been implemented for reading agar column reactions.
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2. Based on 672 separate readings on duplicate SD columns for serum albumin, a cathetometric sighting error (σe) was estimated as 0.036 mm for one investigator; the column to column component of variation (σc) was 0.185 mm.
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3. When duplicate SD columns were measured once each several times during the reaction period, another component of variation, was detected. This, pooled with σe and σc, was estimated as 0.143 mm for 1154 measurements on fractions (II, V)-antifraction reactions. As a general guide—under specific conditions for measurement, time, and temperature—for the mean of one measurement on each of two SD columns to achieve statistical significance over a similar statistic for another reaction, the diffusion difference should equal or exceed 1.96 (0.143 mm) = 0.280 mm (5% probability level) in absolute value. (The normal deviate value, 1.96, pertains only to studies involving, as in this instance, a large number of measurements.)
Footnotes
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↵1 Portions of this report were given at the annual meeting of the American Association of Immunologists, Chicago, 1960. The opinions or assertions contained herein are those of the author and are not to be construed as official or reflecting the views of the School of Aerospace Medicine or the United States Air Force.
- Received July 13, 1961.
- Copyright, 1962, by The Williams & Wilkins Company
- Copyright © 1962 by The American Association of Immunologists, Inc.
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