Sally & Tammy's questionnaire

* Previous summary of the psychometric properties of the SKQ:
1. The questions of the SKQ were somewhat easy for the patients.
2. Both internal consistency and test-retest reliability of the SKQ were moderate.
3. The validity of the SKQ needs further investigation.
4. The responsiveness of the SKQ was low to moderate.
5. The additional 5 items appeared very difficult or very easy. The effect of the 5 items was limited in improving reliability and responsiveness of the SKQ.

* Results of confirmatory factor analysis appear negative:

Summary:
1. They may keep using the original SKQ-25 for consistency because the marginal effects of adding 5 items or deleting 5 easy items of the SKQ-30 were limited.
2. There is a room for improving the psychometric properties of SKQ-25.

Tammy may write a short report on these findings in the future (at least 6 month later).