The quantitative analysis methods discussed in Chapters 4 and 5 require the collection of measured data. Such data represent one type of information which we can collect about phenomena in our environment. Here, measurements relate both to the fundamental properties of objects, where quantities like length extend through space, and to measurement operations performed on individual objects. In the former, measurements are known as extensive properties which form the basis of standard measuring systems such as the SI system in use by most scientists today (Chrisman, 1997: 8-9). However, this view of measurement is only appropriate for physical properties, and is not really applicable to the subject matter of most social scientists. The alternative latter view sees the process of measurement as being separate from the object being measured. This is usually referred to as a representative view of measurement. It was this view that was adopted in the levels of measurement developed by Stevens ( 1946) and listed in Box 3 .1. He identified four levels of measurement: nominal,

Box 3.1 Levels of measurement Nominal Ordinal

Observations are placed in categories, symbolised by numerals or symbols (e.g. , A, B, C, D). Observations can be placed in a rank order, where certain observations are greater than others. Assigned numerals cannot be taken literally (e.g. , first, second, third, fourth).