Measurement scales are used to categorize and/or quantify variables. This presentation describes the four scales of measurement that are commonly used in statistical analysis. This presentation explains the characteristics of nominal, ordinal, interval, and ratio scales with suitable illustrations.

1. Scales of
Measurement
K.THIYAGU,
Assistant Professor,
Department of Education,
Central University of Kerala,
Kasaragod - 671 123, Kerala, India.

2. Scales of measurement refer to ways in which
variables/numbers are defined and categorized.

3. MEASUREMENT SCALES
❑ Nominal scale
❑ Ordinal scale
❑ Interval scale
❑ Ratio scale
Stevents (1946) has recognized some types of scales

4. Nominal
Ordinal
Qualitative
Measures
(Classify into
non-numeric
categories)

5. Interval
Ratio
Quantitative
Measures
(Measurement is
numerical)

6. Measurement Scale
SCALE MAGNITUDE EQUAL ABSOLUTE
ZERO
NOMINAL
X X X
ORDINAL
 X X
INTERVAL
  X
RATIO
  

7. SCALE Indications
Difference
Indicates
Direction of
Difference
Indicates
amount of
Difference
Absolute
Zero
NOMINAL

ORDINAL  
INTERVAL
  
RATIO
   

8. Nominal Scale
❑ 1st level of Measurement Scale in which the
numbers serve as “tags” or “labels” to classify or
identify the objects.
❑ A Nominal Scale usually deals with the non-
numeric variables or the numbers that do not
have any value.

9. Nominal Scale
❑ Simple classification of objects or items into discrete
groups.
❑ Categorical data and numbers that are simply used as
identifiers or names represent a nominal scale of
measurement.

10. Example
Gender
Marital Status
State or residence
College major
Zip code
Student ID
Eye colour
Nominal
Scale

11. ❑ The ordinal scale is the 2nd level of measurement that
reports the ordering and ranking of data without
establishing the degree of variation between them.
❑ Ordinal represents the “order.” Ordinal data is
known as qualitative data or categorical data. It can
be grouped, named and also ranked.
Ordinal Scale

12. Ordinal Scale
❑ Scale involving ranking of objects, persons, traits,
or abilities without regard to equality of difference.
❑ Eg. Line up the students of a class according to
height or merits.

13. Example
• Ranking of school students – 1st, 2nd, 3rd, etc
• Ratings in restaurants
• Evaluating the frequency of occurrences
• Very often
• Often
• Not often
• Not at all
• Assessing the degree of agreement
• Totally agree
• Agree
• Neutral
• Disagree
• Totally disagree
Ordinal
Scale

14. Interval Scale
❑ Interval scales are also called equal unit scales.
❑ Scale having equal difference between successive
categories
❑ Eg. Intelligence scores, personality scores

15. The interval scale is the 3rd level of measurement
scale. It is defined as a quantitative measurement
scale in which the difference between the two
variables is meaningful.
In other words, the variables are measured in an
exact manner, not as in a relative way in which the
presence of zero is arbitrary.
Interval Scale

16. Example:
❑ Likert Scale
❑ Net Promoter Score(NPS)
❑ Bipolar Matrix Table
Interval Scale

17. Ratio Scale
❑ The ratio scale is the
4th level of
measurement scale,
which is quantitative.
❑ The ratio scale has a
unique feature. It
possesses the character
of the origin or zero
points.

18. Ratio Scale
❑ Scale having an absolute zero, magnitude and equal intervals
❑ Eg. Height , weight, number of students in various class

19. • What is your weight in Kgs?
• Less than 55 kgs
• 55 – 75 kgs
• 76 – 85 kgs
• 86 – 95 kgs
• More than 95 kgs
Ratio Scale

21. SCALE Typical statistics
Descriptive Inferential
Nominal Percentage, mode Chi-square, Binomial test
Ordinal Median Rank order correlation
Interval Mean, range, standard
déviation
Product moment
correlation, t-test, factor
analysis
Ratio Geometric mean Coefficient of variation

22. ThankYou
Jai Bharat!