Chapter 12: Scales and Measurements

Chapter 12: Scales and Measurements

Overview

Before you can put data into a database, you actually need to think about how it will be represented and manipulated. This is true not just of SQL but of any record keeping system. If you don?t believe that the representation is important, then try taking a square root in Roman numerals, in Mayan numerals, and in Hindu-Arabic numerals. The numbers are all the same, but the numerals are different, and it makes a world of difference in what you can do with the data.

This chapter deals with the representation of individual attributes of the entities we are trying to model in a database.

12.1 Measurement Theory

Measure all that is measurable and attempt to make measurable that which is not yet so.? Galileo

This is a short introduction to measurement theory and scales, so that you will have a good theoretical foundation to do any practical work. Besides, this is interesting stuff. Trust me. Measurement is not just assigning numbers to things or their attributes so much as it is assigning to things a structural property that can be expressed in numbers or other computable symbols. This structure is the scale used to take the measurement; the numbers or symbols represent units of measure.

Scales are classified into types by the properties they do or do not have. The properties with which we are concerned are the following:


	1.	A natural origin point on the scale. This is sometimes called...

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Chapter 12: Scales and Measurements

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