The Practical Necessity of Units

"Chapter 35. There shall be one measure of wine throughout Our kingdom, and one of ale, and one measure of corn, to wit, the London quarter, and one breadth of dyed cloth, ..., to wit, two ells [3 yards] within the selvages [borders]. As with measures so shall it be with weights."

John, King of England, in Magna Carta [Great Charter], Monday, June 15, 1215 at Runnymede. Affixed with the King's Great Seal on June 19.

"We the People of the United States ... do ordain and establish this Constitution for the United States of America.

Article I. Section 8. The Congress shall have Power [5] To coin money ..., and fix the Standard of Weights and Measures;"

ratified June 21, 1788, instituted April 30, 1789.

"If one attempts to measure even so simple a thing as spelling, one is hampered by the fact that there exist no units in which to measure. One may arbitrarily make up a list of words and observe ability by the number spelled correctly. But if one examines such a list one is struck by the inequality of the units. All results based on the equality of anyone word with any other are necessarily inaccurate."

Edward L. Thorndike (1904) An Introduction to the Theory of Mental and Social Measurements. New York:The Science Press, p. 5.

"The task of developing valid, reliable interval measurement is not a technical detail that can be postponed indefinitely while the main efforts in sociological research are devoted to substantive theory construction; rather it is the central theoretical and methodological problem in scientifically-oriented sociology."

Wilson, Thomas P. (1971) Critique of ordinal variables. Social Forces 49: 432-444.

Science should be as simple as possible, but no simpler.

Albert Einstein

The Practical Necessity of Units. Thorndike E. L. et al. … Rasch Measurement Transactions, 1997, 11:1 p. 545.

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