RM MCOM LEVELS OF MEASUREMENT

LEVELS OF MEASUREMENT

    A level of measurement is the precision by which a variable is measured. For 50 years, with few detractors, science has used the Stevens (1951) typology of measurement levels. There are three things to remember about this typology: (1) anything that can be measured falls into one of the four types; (2) the higher the type, the more precision in measurement; and (3) every level up contains all the properties of the previous level. The four levels of measurement, from lowest to highest, are:

·         Nominal

·         Ordinal

·         Interval

·         Ratio 

    The nominal level of measurement describes variables that are categorical in nature. The characteristics of the data you're collecting fall into distinct categories. If there are a limited number of distinct categories (usually only two), then you're dealing with a discrete variable. If there are an unlimited or infinite number of distinct categories, then you're dealing with a continuous variable. Nominal variables include demographic characteristics like sex, race, and religion. 

    The ordinal level of measurement describes variables that can be ordered or ranked in some order of importance. It describes most judgments about things, such as big or little, strong or weak. Most opinion and attitude scales or indexes in the social sciences are ordinal in nature. 

    The interval level of measurement describes variables that have more or less equal intervals, or meaningful distances between their ranks. For example, if you were to ask somebody if they were first, second, or third generation immigrant, the assumption is that the distance, or number of years, between each generation is the same. All crime rates in criminal justice are interval level measures, as is any kind of rate. 

    The ratio level of measurement describes variables that have equal intervals and a fixed zero (or reference) point. It is possible to have zero income, zero education, and no involvement in crime, but rarely do we see ratio level variables in social science since it's almost impossible to have zero attitudes on things, although "not at all", "often", and "twice as often" might qualify as ratio level measurement.

    Advanced statistics require at least interval level measurement, so the researcher always strives for this level, accepting ordinal level (which is the most common) only when they have to. Variables should be conceptually and operationally defined with levels of measurement in mind since it's going to affect how well you can analyze your data later on.