Variables: Types and their Operational Definitions Unit III: Problem identification formulation of research objectives and hypothesis (as part of M.Optom Curriculum of Pokhara University, Nepal)

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