scales of measurement (Nominal, Ordinal, Interval, Ratio)

Scales of measurement is the rule which is used in assigning the number or symbol to observation or items. In other words, the principle or the rule of correspondence used for measurement is called scale. It is, simply, a range of levels or numerals used for measuring something.

Measurement is the process of assigning the numbers or symbols to the objects or events based on pre-determined set of rules. The term ‘measurement’ means the mapping of objects of one set into the objects of another set. It is a device by which individuals are distinguished on the variables of area under study .Let’s talk about Scales of Measurement and its type below:

Generally, there are four types of measurement scales of variable

  1. Nominal Scale.
  2. Ordinal Scale.
  3. Interval Scale.
  4. Ratio Scale.

Scales of measurement Nominal

  • Nominal scale is the lowest scale of measurement.
  • The numbers or symbols are assigned to classify the objects or events having some attributes.
  • The production of goods as defective or non-defective, success or failure, habits, sex, numbers of football players etc are some examples which are measured by nominal scale.
  • In this scale, the basic mathematical operation can’t be used.
  • Thus, the basic property of nominal scale is just to differentiate the objects by classifying them into different classes.

Ordinal measurement Scale:

  • An ordinal scale of measurement describes the order of objects or events or phenomenon.
  • The ordinal scales of measurements are used only for ranking or ordering to the objects but not relative size of the objects.
  • In this scale, the numbers or symbols are assigned according to the rank of the objects.
  • For example, suppose our characteristic under study is the attitude of people towards certain facts such as positive, negative and neutral.
  • Then we may assign numbers 1 for positive, 2 for negative and 3 for neutral.
  • Even in ordinal scale, we can’t perform the basic mathematical operation but we can use less then or more than sign.
  • It is used for measuring the level of performance, level of solders, level of education etc.
  • The basic property of the scale is to differentiate the objects as in nominal scale and then rank ordering them.
  • It may be considered as an extended form of nominal scale.

Interval measurement Scale

  • The basic property of this scale is to distinguish the objects from the others by rank ordering them and making the intervals equal between successive points on the scale.
  • One common example of interval scale is temperature scale.
  • The interval between 200 C and 300 C is same as that between 500 C and 600 C.
  • The ratio between the numbers on the scale are not meaningful so multiple and division operation can’t be performed but simply difference can be taken into the consideration.
  • An interval scale has no true (absolute) zero point to indicate the absence of the particular characteristics.
  • Some examples of interval data in which the interval scale is used are temperature, sea level etc.
  • It is considered as an extended form of an ordinal scale.

Ratio Measurement Scale

  • Ratio scale is the highest form of measurement.
  • On a ratio scale, measurements begin at a true zero point and the scale has equal intervals.
  • Thus, the ratio scale is the extension of the interval scales since it corporate all the properties of interval scale.
  • Ratio scales are mostly used in the physical science and engineering.
  • The variables measured on the ratio scales are mass, length, breadth, time, energy, volume etc.
  • While considering these four measurement scale it should be noticed that each scale gets improved by incorporating anew property.

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