The document discusses the concept of variables in research, outlining their definitions, types, and operational definitions within the framework of quantitative research. It categorizes variables based on causal relationships, study design, and measurement units, providing examples for clarity. The document emphasizes the importance of operational definitions for measuring variables effectively in research studies.

1. Variables:
Types and Operational Definitions
Rabindra Adhikary
ravinems@iom.edu.np
M. Optom, 1st Batch (2019)
Tilganga Institute of Ophthalmology
Pokhara University
Facilitator: Mohan Krishna Shrestha, TIO Date: 13 June 2019
Main Topic: Unit III: Problem identification formulation of research objectives
and hypothesis (as part of M.Optom Curriculum of Pokhara University, Nepal)

2. variables
• Learning Objectives:
– Define and explain variables
– Define and explain the operational definitions of
variables with example

3. What is a variable
• Image, perception or a concept
– Which is measurable (Measurability)
– Whose value is variable (Variability)
• Key to Quantitative research
• Provides rational ground (after analysis) to
come to a conclusion

4. Kerlinger:
• ‘A variable is a property that takes on different
values. Putting it redundantly, a variable is
something that varies ... A variable is a symbol
to which numerals or values are attached’
(1986)

5. • Black and Champion define a variable as
‘rational units of analysis that can assume any
one of a number of designated sets of values’
(1976)

6. Concepts vs Variable

7. Types of Variables
• Generally, variables are classified on three
basis:
– Causal Relationship
– Study design
– Unit of measurement

9. Casual Relationship
• Change variable (Independent)
– Brings about change in the phenomenon or situation
under observation
• Outcome variable (Dependent)
– Effects or consequences of change variables
• Influencing variable (Extraneous)
– Influences or affects the link between cause-and-
effect variables
• Linking Variable (Intervening)
– Necessary to complete the relationship between
cause and effect variables

10. • Intervening variables, also called confounding
variables because it links the independent and
independent variables
– What was the actual cause?
• Necessary to establish the link between
dependent and independent variables

11. Types of variables in causal
relationship

12. Example

13. Variables
from the viewpoint of study design
• Active Variables
– Can be controlled, changed or manipulated
– Contents, structure, testability
• Attribute variables
– Can’t be manipulated, changed or controlled
– Age, weight, gender, etc

14. From the viewpoint of
unit of measurement
• Categorical variables
– Qualitative
– Nominal and ordinal scales
• Continuous variables
– Quantitative
– Interval and ratio scales

15. Video 1

16. Video 2

17. Continuous?
• These variables can have any numeric value
– Weight of a person : 60kg, 61.7kg, 62.4kg
– Height of a person: 5.5”, 6.2”, 7.1”

18. Operational Definitions
• A statement that specifies the procedures
(the operations) used to measure the variable
• operational definition of a variable is the
specific way in which it is measured in that
study

19. Example
• Intelligence
– Use 5 min
– Execute task

20. ??
• Physical Attractiveness
• Depression
(ask questions to the audience to set the
operational definitions of these variables)

22. Comparison

23. Thank You