Units for Measurement in Research

A unit is a quantity used as a standard, in terms of which other quantities of the same kind can be measured or expressed. We discussed earlier measuring the height of a person and used the inch as the unit of length. The inch itself is an arbitrarily defined quantity, meaning there is nothing in nature to recommend this particular length over any other length. If we want to measure the length of a tennis court, we may use the foot as a better unit, and if we want to express the distance between Boston and New York, we may use the mile as a convenient unit. The relations among the inch, foot, and mile, meaning for instance, how many inches make up a foot, are again arbitrary decisions. These are neither nature dictated nor made inevitable by reason; they are purely manmade. But all those who use these units are bound by a com­mon agreement, referred to as a standard. A standard inch is the same length whoever uses it, whenever, wherever. Similar consid­erations apply to units of weight: the pound, ounce, ton, and so forth. The units of time—the year, day, hour, minute, and sec­ond—are no different in this regard, except that a day is about the same duration as the earth takes to make a rotation on its own axis.

Source: Srinagesh K (2005), The Principles of Experimental Research, Butterworth-Heinemann; 1st edition.