Steps in Scale Development (DeVellis, 2003)

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