ILLINOIS WATER TREATMENT COMPANY

ments—that the "universe" of end lessly repeated analyses shows a normal (Gaussian) distribution of errors, are we allowed to interpret the findings...
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procedure. We do not need many measurements to establish an ana-

if it is curve known in advance that this will be a straight line. Only if we are sure— from the results of previous experiments—that the “universe” of endlessly repeated analyses shows a normal (Gaussian) distribution of errors, are we allowed to interpret the findings from a few repeated analyses in terms of Student’s f-distribution. This list of examples could be continued ad nauseam. It is worthwhile to be aware of the powerful part played by pre-information in practically all analytical procedures, all the more because uncontrolled pre-information is the loophole by which wrong or obsolete conventional ideas may enter.

lytical (calibration)

IWT

color change

tells you have

pure water