2-Measurement Scale

Types of Measurement Scale

Measurement is a process of assigning numbers/values to a physical condition, phenomenon, or status. There are four different scales of measurement. The data can be defined as being one of the four scales. The four types of scales are:

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

Nominal scale

  • Example: Name, Board, Male, Female, Blood group, etc.
  • A nominal scale consists of a set of categories that have different names.
  • Nominal is naming categories without any order. You cannot put it in descending or ascending order.
  • When the data for a variable consists of labels or names used to identify the characteristic of an observation, the scale of measurement is considered a nominal scale.
  • Sometimes nominal variables might be numerically coded. For example, Men are coded as 1 and Women as 2.
      • If we say – the temperature inside the room is comfortable – Then the temperature as a variable is nominal.
      • If we say the outside Temperature is uncomfortable – Then the temperature as a variable is nominal.

         

Ordinal scale

  • Example: Customer rating for services offered as excellent/good/poor.
  • Ordinal – relating to the order of something in a series.
  • The data obtained are the labels—excellent, good, or poor
      • Individual data has properties of nominal data. Excellent is nominal data. But when put together as excellent/good/poor, it becomes ordinal data.
      • Data can be ranked or ordered, with respect to the customer rating of service quality.
  • An ordinal scale consists of a set of categories that are organized in an ordered sequence. Measurements on an ordinal scale rank observations in terms of size or magnitude.
  • Data exhibits properties of nominal data and the order or rank of data is meaningful, the scale of measurement is considered an ordinal scale.
      • If we say – the temperature inside the room is cold outside the temperature is warm and in the desert area temperature is hot – Then the temperature as a variable is ordinal.

Other Examples:

  • Restaurants food rating
        • Very good
        • Good
        • Not good
        • Poor
  • Performance of school students
        • Ist
        • IInd
        • IIIrd
  • Evaluating the mobile signal breakdown
        • Very often
        • Often
        • Not often
        • Not at all
  • Survey question
        • Totally agree
        • Agree
        • Neutral
        • Disagree
        • Totally disagree

Interval scale

  • Example: Percentile, CGPA, Grade, Temperature in degrees Fahrenheit (200F), Temperature in degree centigrade (700C), pH value, SAT score, Specific gravity, etc.
  • An interval scale consists of ordered categories that are all intervals of exactly the same size. Equal differences between numbers on the scale reflect equal differences in magnitude.
  • A zero point on an interval scale is arbitrary and does not indicate a zero amount of the variable being measured.
      • On the Temperature Celsius scale: zero degree (0oC) temperature is defined as the temperature of ice and water mixture in equilibrium at 1 atmosphere. Therefore 0oC is a reference point, not an absolute zero. Hence Celsius scale is an interval scale.
      • On the Fahrenheit scale: Zero degree 0oF temperature is considered as the freezing temperature of brine. Therefore 0oF is a reference point, not an absolute zero. Hence Fahrenheit scale is an interval scale.
  • Interval scale has Ordinal data properties + fixed interval value. Example: temp 20OC, 21OC, 220C….., the temp can be taken in an interval of 10C.
  • The interval scale is quantitative as it can quantify the difference between the values. It allows calculating the mean and median of the variables
      • If we say – the temperature inside the room is comfortable and the outside temperature is uncomfortable – Then the temperature as a variable is nominal.
      • If we say – the temperature inside the room is cold outside the temperature is warm and in the desert area temperature is hot – Then the temperature as a variable is ordinal.
      • If we say – the temperature inside the AC room is 22°C and the temperature outside the room is 45°C – Then the temperature as a variable is Interval.

Ratio scale

  • Example: height, weight, age, marks, speed, distance, Temperature in Kevin, light intensity, etc.
  • A ratio scale is an interval scale + with an absolute zero point.
  • The ratio scale has an absolute zero
  • It doesn’t have negative numbers, because of its zero-point feature.
      • The temperature scale in Kelvin is a ratio scale variable because its zero value is absolute zero (0ok). 0o K is the lowest possible temperature.
  • Ratio is a numerical value therefore it can be added, subtracted, multiplied, or divided
      • If we say – the temperature inside the AC room is 22°C and the temperature outside the room is 45°C – Then the temperature as a variable is Interval.
      • If we say – the temperature inside the AC room is 295°K (273+ 22) and the temperature outside the room is 318°K (273+45) – Then the temperature (measured on the Kelvin scale) as a variable is Ratio.

Comparison of Nominal scale, Ordinal scale, Interval scale, and Ratio scale:

  • Refer comparison in the below table

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