Psychologist Stanley Smith Stevens (1946) developed the best-known classification with four levels, or scales of measurement such as Nominal, Ordinal, Interval, and Ratio. This presentation slide describes the four-level of scales with illustrations.

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

2. SCALES OF MEASUREMENT
❑ Nominal scale
❑ Ordinal scale
❑ Interval scale
❑ Ratio scale
Psychologist Stanley Smith Stevens (1946)
developed the best-known classification with
four levels, or scales of measurement
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4. Measurement Scale
SCALE MAGNITUDE EQUAL
INTERVALS
ABSOLUTE
ZERO
NOMINAL
X X X
ORDINAL  X X
INTERVAL
  X
RATIO
  
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5. Nominal Scale
❑ Simple classification of objects or
items into discrete groups.
❑ Eg. Naming of streets, naming of
persons and cars
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6. Nominal scales are used for labeling variables, without
any quantitative value.
“Nominal” scales could simply be called “labels.”
A good way to remember all of this is that “nominal” sounds a lot like
“name”
Nominal scales are kind of like “names” or labels.
At this level, we cannot perform any quantitative mathematical operations,
such as addition or division. These would not make any sense.
Nominal Scale
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7. 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.
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8. Ordinal scales are typically measures of non-numeric
concepts like satisfaction, happiness, discomfort, etc.
With ordinal scales, the order of the values is what’s
important and significant, but the differences between
each one is not really known.
Ordinal” is easy to remember because is sounds like
“order”
Ordinal Scale
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9. Interval Scale
❑ Interval scales are also called equal unit
scales.
❑ Scale having equal difference between
successive categories
❑ Eg. Intelligence scores, personality scores
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10. Interval scales are numeric scales in which we know both
the order and the exact differences between the values.
At Interval level, we will have meaningful differences
between values.
At the interval level, we have addition and subtraction to
work with.
With interval data, we can add and subtract, but cannot
multiply or divide.
Interval Scale
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11. Ratio Scale
❑ Scale having an absolute zero, magnitude
and equal intervals
❑ Eg. Height , weight, number of students in
various class
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12. Good examples of ratio variables
include height and weight.
Ratio scales provide a wealth of
possibilities when it comes to
statistical analysis. These variables
can be meaningfully added,
subtracted, multiplied, divided
(ratios).
Ratio Scale
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16. 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
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17. Thank
Jai Bharat!
You
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