Statistical methods in analytical chemistry.

Plan for Studying Accuracy and Precision of Analytical Procedure

“…The presence of curvature if appreciable would constitute a serious limitation to the usefulness of the analytical procedure. When it is possible to make the duplicate determinations on exactly the same quantity of added material, the increase in the standard deviation attributable to curvature may be estimated by an analysis of variance (5,8). Tables V and VI list the values of the slopes and intercepts and their standard errors for each of the five series of titrations calculated from the least squares theory for linear regression (4,16).…”

Determination of Lipid Phosphorus in Ultramicro Quantities of Serum

“…where the error of spectrophotometers is minimal (Tw,\^nan and Lothian, 1933). "When using the simplified procedure, the possible influence ol' inslrumcutal errors on reproducibility of absorbance measurements should be considered (Cannon and Butterworth, 1953;Caster, 1951;Mandel, 1949). However, in routine work variation between phosphorus unknowns from methodological and instrumental sources may be very small compared with that due to normal variation between animals and there are often occasions when the gain in information, resulting from the increased number of determinations of phosphorus (or relevant unknowns), made possible by the use of the standard regression, more than compensates for any slight loss in precision in determination of the phosphorus unknowns.…”

Experimental Statistics

“…Its principal advantage is in the detection of so-called interaction effects. In many cases, an investigation involving all possible combinations would be prohibitively large; however, there now exist systems of constructing so-called "frac-tional factorials" in which the number of combinations is drastically reduced without sacrificing any important information (5, 27, 36, 50,66,76,88,100,104,106,111,133,148).…”