CONCEPTS
AND
VARIABLES
• An image, perception or concept that is
capable of measurement – hence capable
of taking on different values – is called a
variable.
• In other words, a concept that can be
measured is called a variable.
• According to 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: 27)
The difference between a concept and a
variable
• Measurability is the main difference
between a concept and a variable.
• Concepts
are
mental
images
or
perceptions and therefore their meanings
vary markedly from individual to individual,
whereas variables are measurable,
though, of course, with varying degrees of
accuracy.
• A concept cannot be measured whereas a
variable can be subjected to measurement
• It is therefore important for the concepts to
be converted into variables (either directly
or through a set of indicators) as they can
be subjected to measurement,
Types of variables
•
•
•
•
independent variables
dependent variables
extraneous variables
intervening variables
Extraneous variables
Intervening variables
Types of Variables
Quantitative
Qualitative
Continuous
Discrete
Interval
Ratio
E.g.
E.g.
E.g.
No. of children in
each family
Age (In years),
Body Mass
Index (BMI)
No. of relapses or
recurrences
No. of attacks of
asthma per week
BP (mmHg),
Binary /
Dichotomous
E.g.
E.g.
Mortality:
Blood Group:
Alive/Dead
O, A, B, AB
Marital Status:
Disease:
Yes/No
Height (In Cms),
Weight (In Kgs)
Nominal
Recovery:
Recovered/ Relapse
Treatment Group:
New/Standard
Single/ Married/
Divorced/
Separated/ Widow
Ordinal
E.g.
Health Status:
Good/
Moderate/
Bad
Pain:
Mild/
Moderate/
Severe
Measurement scale into four
categories
•
•
•
•
nominal or classificatory scale;
ordinal or ranking scale;
interval scale;
ratio scale.