SCALE OF MEASUREMENT
Scaling is the procedure for assignment of numbers or other symbols to a property of objects in order to impart some of the characteristic of numbers to the properties in question. We can assign numbers to indicate the properties of objects.
Types of measurement scales
a)Nominal Scale: – Nominal scale is simple a system of assigning number or symbols to event in order to label them. For example, we use nominal scale if we want to categorize male and female. These numbers are just convenient labels and as such have no quantitative value.
Nominal scale is a least power full tool of measurement. It indicates no order or distance relationship and has no arithmetic origin. It’s simply describing difference between things by assigning them to categories.
In research activities a YES/NO scale is nominal. It has no order and there is no distance between YES and NO.
b)Ordinal Scale: – Ordinal scale only permits the ranking of the item from highest to lowest. The ordinal scale places events into order. The ordinal variable is one where the order matters but not the difference between values. In this scale we can say that which element is highest and which is lowest but we cannot make any comparison. It just tells us which one is highest or which one is lowest. Rank 1 means it is ranked higher than rank 2. The difference in ranks 1 and 2 is not necessarily be equal to the difference between 2 and 3.
The simplest ordinal scale is a ranking. When a market researcher conducts a survey to rank 5 types of ice cream from most favourful to least favourful, he/she uses an ordinal scale of preference.
Ranking Scale example
Rank the following computers (from most preferable = 1 to least preferable = 7)
- IBM PC
c)Interval Scale: –In this scale we provide the intervals. The intervals are adjusted in terms of some scale that has been established as basis for making the units equal. The distance between the rates 1 and 2 is equal to the difference between 2 and 3 in interval scale; but in ordinal scale this difference is not same.
Interval scale is used in most of the behavioural researches to measure the attitudes on 1 to 5 or 1 to7 or 1 to 10 scales. This is also called rating scale. We use an interval scale when we rate the satisfaction level with a particular brand of product on a 7 point scale, from Dissatisfied to Satisfied.
Rating scale Example
Rate this Product on 1 to 5 scales.
- Very good
d)Ratio Scale: – Ratio scale represents the actual amounts of variables. Measurement of physical dimensions such as weight, height, distance etc. is possible with the ratio scales. One can make statements like the writing speed of X is twice as good as that of Y” by using the ratio scale.
Metric data is any reading which is measured at interval or ratio scale. As opposed to non Metric data which can be nominal or ordinal. Ex: weight, height, distance, revenue, cost etc., all of them are interval scales or above. Hence they are metric data. On the other hands, satisfaction ratings, Yes/No responses, Male/Female readings etc., are non Metric Data.