1. CONCEPT TO BE INCLUDED
Variable
Value

2. Variables as ‘constructions’

3. aim
Variables are ‘constructed’ by researchers

4. Example: AGE

5. Theoretical variable(s)
Research questions
Research questions are about theoretical variables describing units
Theoretical variable(s)
Unit (s)
Data

6. Variables (DEF.)
A ‘variable’ is a complete and mutually exclusive set of
attributes or values.
Example: Age (of a human being) has values: 0 to120.
Every unit (human being) has an age (complete) + you cannot be both 10 and 20 (mutually exclusive)

7. Attributes or Values?
The words ‘values’ and ‘attributes’ refer to the same thing, however
‘values’ is more often used to refer to ‘numerical’ attributes (age or weight)
‘attributes’ is more often used to refer to ‘non-numerical’ attributes (colors, religions)
In SPSS and similar programs, even attributes like colors have ‘numbers’.

8. Five levels of measurement Dichotomy / Dummy
SPSS terminology:
Dichotomy / Dummy
Nominal
Ordinal
Interval
Ratio
NOMINAL
ORDINAL
SCALE

9. Ratio
If the values can be ordered, the distance between the values is known, and there is a meaningful ‘zero’ point, the variable is called a ‘ratio’ variable Example: Age of a person (Trick: you can say ‘twice as old’: 30 is twice as old as 15)

10. Age as a ‘ratio scale’
Age of a person Measured or defined in: YEARS? MONTHS? DAYS? …

11. Ordinal Example: 0-18 19-35 36-64 65-older
If the values can be ordered, but the distance between the values is unknown, the variable is called ‘ordinal’ Age in categories
Example:
0-18
19-35
36-64
65-older
What do we know about the difference between someone in 1 and someone in 3?
Or even two people within 1?

12. Dichotomy If a variable has two attributes only: dichotomy. Age 0-18
Age over 18
What do we know about the difference between someone in 1 and someone in 2?

13. WHICH CONCEPTUALIZATION IS ‘BEST’?
Is depends on what you expect: Babies: ratio variable in days, weeks or months Participation in elections: ordinal variable Effects of being allowed to drive a car: dichotomy

14. THIS MICROLECTURE Variables are ‘constructed’ by researchers
How they are constructed depends on
The research question
What you ‘think’ (theory)