1. Steps in Scale Development (DeVellis, 2003)

2. Steps in Scale Development (DeVellis, 2003)
Determine clearly what it is you want to measure.
Theory as an aid to clarity.
Specificity as an aid to clarity.

3. Steps in Scale Development (DeVellis, 2003)
Determine clearly what it is you want to measure.
Theory as an aid to clarity.
Measuring “elusive phenomena that cannot be directly observed”.
Specificity as an aid to clarity.
Do you wish to measure a broad, general construct or a context-specific construct?

4. Steps in Scale Development (DeVellis, 2003)
Determine clearly what it is you want to measure.
Theory as an aid to clarity.
Measuring “elusive phenomena that cannot be directly observed”.
Specificity as an aid to clarity.
Do you wish to measure a broad, general construct or a context-specific construct?
Locus of control example

5. Steps in Scale Development (DeVellis, 2003)
Determine clearly what it is you want to measure.
Theory as an aid to clarity.
Measuring “elusive phenomena that cannot be directly observed”.
Specificity as an aid to clarity.
Do you wish to measure a broad, general construct or a context-specific construct?
Locus of control example
2. Generate an item pool.

6. Steps in Scale Development (DeVellis, 2003)
Determine clearly what it is you want to measure.
Theory as an aid to clarity.
Measuring “elusive phenomena that cannot be directly observed”.
Specificity as an aid to clarity.
Do you wish to measure a broad, general construct or a context-specific construct?
Locus of control example
2. Generate an item pool.
3. Determine the format for measurement.

7. Steps in Scale Development (DeVellis, 2003)
Determine clearly what it is you want to measure.
Theory as an aid to clarity.
Measuring “elusive phenomena that cannot be directly observed”.
Specificity as an aid to clarity.
Do you wish to measure a broad, general construct or a context-specific construct?
Locus of control example
2. Generate an item pool.
3. Determine the format for measurement.
4. Have item pool reviewed.

8. Steps in Scale Development (DeVellis, 2003)
Determine clearly what it is you want to measure.
Theory as an aid to clarity.
Measuring “elusive phenomena that cannot be directly observed”.
Specificity as an aid to clarity.
Do you wish to measure a broad, general construct or a context-specific construct?
Locus of control example
2. Generate an item pool.
3. Determine the format for measurement.
4. Have item pool reviewed.
5. Consider inclusion of validation items.

9. Steps in Scale Development (DeVellis, 2003)
Determine clearly what it is you want to measure.
Theory as an aid to clarity.
Measuring “elusive phenomena that cannot be directly observed”.
Specificity as an aid to clarity.
Do you wish to measure a broad, general construct or a context-specific construct?
Locus of control example
2. Generate an item pool.
3. Determine the format for measurement.
4. Have item pool reviewed.
5. Consider inclusion of validation items.
6. Administer items to pilot sample.

10. Steps in Scale Development (DeVellis, 2003)
Determine clearly what it is you want to measure.
Theory as an aid to clarity.
Measuring “elusive phenomena that cannot be directly observed”.
Specificity as an aid to clarity.
Do you wish to measure a broad, general construct or a context-specific construct?
Locus of control example
2. Generate an item pool.
3. Determine the format for measurement.
4. Have item pool reviewed.
5. Consider inclusion of validation items.
6. Administer items to pilot sample.
7. Evaluate items.

11. Steps in Scale Development (DeVellis, 2003)
Determine clearly what it is you want to measure.
Theory as an aid to clarity.
Measuring “elusive phenomena that cannot be directly observed”.
Specificity as an aid to clarity.
Do you wish to measure a broad, general construct or a context-specific construct?
Locus of control example
2. Generate an item pool.
3. Determine the format for measurement.
4. Have item pool reviewed.
5. Consider inclusion of validation items.
6. Administer items to pilot sample.
7. Evaluate items.
8. Produce final scale.

12. Steps in Scale Development (DeVellis, 2003)
Determine clearly what it is you want to measure.
Theory as an aid to clarity.
Measuring “elusive phenomena that cannot be directly observed”.
Specificity as an aid to clarity.
Do you wish to measure a broad, general construct or a context-specific construct?
Locus of control example
2. Generate an item pool.
3. Determine the format for measurement.
4. Have item pool reviewed.
5. Consider inclusion of validation items.
6. Administer items to pilot sample.
7. Evaluate items.
8. Produce final scale.

13. Steps in Scale Development (DeVellis, 2003)
Determine clearly what it is you want to measure.
Theory as an aid to clarity.
Measuring “elusive phenomena that cannot be directly observed”.
Specificity as an aid to clarity.
Do you wish to measure a broad, general construct or a context-specific construct?
Locus of control example
2. Generate an item pool.
3. Determine the format for measurement.
4. Have item pool reviewed.
5. Consider inclusion of validation items.
6. Administer items to pilot sample.

14. 6. Administer items to pilot sample.

15. Administer items to pilot sample.
For focus group

16. Administer items to pilot sample.
For focus group
Pretest sample should resemble study sample.
Sample size 3 to 9
Discuss questions with respondents to find confusion or ambiguity.
Refine answer options.
Time how long it takes.

17. Administer items to pilot sample.
For pilot study

18. Administer items to pilot sample.
For pilot study
Pretest sample should resemble study sample.
n>20
Study descriptive statistics of items.
Refine answer options.
Time how long it takes. Test reliability.
Revise scale based on reliability information
Examine variance among respondents.

19. Steps in Scale Development (DeVellis, 2003)
Determine clearly what it is you want to measure.
Theory as an aid to clarity.
Measuring “elusive phenomena that cannot be directly observed”.
Specificity as an aid to clarity.
Do you wish to measure a broad, general construct or a context-specific construct?
Locus of control example
2. Generate an item pool.
3. Determine the format for measurement.
4. Have item pool reviewed.
5. Consider inclusion of validation items.
6. Administer items to pilot sample.
7. Evaluate items.
8. Produce final scale.

20. Steps in Scale Development (DeVellis, 2003)
Determine clearly what it is you want to measure.
Theory as an aid to clarity.
Measuring “elusive phenomena that cannot be directly observed”.
Specificity as an aid to clarity.
Do you wish to measure a broad, general construct or a context-specific construct?
Locus of control example
2. Generate an item pool.
3. Determine the format for measurement.
4. Have item pool reviewed.
5. Consider inclusion of validation items.
6. Administer items to pilot sample.
7. Evaluate items.
8. Produce final scale.

21. Locus of control example

22. Locus of control example
Internal-External Scale (Rotter, 1966)
Generalized, Broad, One dimension
Locus of Control

23. Locus of control example
Internal-External Scale (Rotter, 1966)
Generalized, Broad, One dimension
Locus of Control
Multidimensional Scale (Levinson, 1973)
Generalized, Three dimensions
One’s Self
Powerful Others
Luck or Chance

24. Locus of control example
Internal-External Scale (Rotter, 1966)
Generalized, Broad, One dimension
Locus of Control
Multidimensional Scale (Levinson, 1973)
Generalized, Three dimensions
One’s Self
Powerful Others
Luck or Chance
Multidimensional Scale (Wallston, Wallston & DeVellis, 1978)
Health, Three dimensions
One’s Self
Powerful Others
Luck or Chance
Health Health Health