An evaluation of the Circadian Type Questionnaire

Area of Science:

• Chronobiology
• Psychometrics
• Occupational Health

Background:

• The Circadian Type Questionnaire (CTQ) is used to assess individual circadian rhythms.
• Previous research has not fully established its psychometric robustness.
• Understanding circadian types is crucial for optimizing shiftwork schedules and worker well-being.

Purpose of the Study:

• To evaluate the psychometric properties of the Circadian Type Questionnaire (CTQ).
• To assess the test-retest reliability and longer-term stability of CTQ scores.
• To determine the suitability of the CTQ for predicting adaptation to shiftwork.

Main Methods:

• The study involved 445 students to evaluate the CTQ's psychometric properties.
• Test-retest reliability was assessed over three months in a subgroup (n=36).
• Longer-term stability was examined over nine months in a subgroup (n=36) exposed to shiftwork.

Main Results:

• The CTQ scales demonstrated a lack of internal consistency.
• The proposed factor structure was not replicated, suggesting cultural variations.
• Test-retest reliability was poor for the V and M scales; longer-term stability showed decreases in R_s and M scores.

Conclusions:

• The CTQ exhibits significant psychometric flaws.
• The current CTQ scales require substantial improvement for reliable use.
• The CTQ is not yet suitable as a predictive tool for shiftwork adaptation.