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May 4, 1970

The "Normal" Range

Author Affiliations

Ipswich, England

JAMA. 1970;212(5):883-884. doi:10.1001/jama.1970.03170180159034

To the Editor.—  The attempt by Dr. Elveback and her colleagues to exorcise the ghost of Gauss (211:69-75, 1970), calls for some comment.As they state, Gauss was primarily concerned with the theory of errors, but the components in an error distribution are analogous to those in any other type of measurement. If I measure the length of a table with a ruler I should get a single answer; however, the lengths of the table and the ruler vary with temperature and humidity, and there are parallax errors in reading the ruler, so I do not get a constant reading. Since there are three definable sources of variation, the range of measurements should be predictable; unfortunately, the three primary causes of variation, temperature, humidity, and parallax are themselves resultants of more remote causes, so that ultimately there are not three, but an indefinitely large number of determinant factors; as