Measurement properties of the Shiftwork Survey and Standard Shiftwork Index

Area of Science:

• Occupational Health Psychology
• Psychometrics
• Industrial/Organizational Psychology

Background:

• The Shiftwork Survey (SS) and Standard Shiftwork Index (SSI) are key tools for shiftwork research.
• Previous validation was limited, necessitating independent assessment of their measurement properties.

Purpose of the Study:

• To evaluate the psychometric properties of the SS and SSI scales in an industrial shiftworker sample.
• To identify scales requiring refinement for improved accuracy in shiftwork studies.

Main Methods:

• Confirmatory factor analysis (CFA) was used to assess scale structure.
• Reliability (Cronbach's alpha) and item response theory (IRT) analyses were conducted.
• The study involved 370 primarily male industrial shiftworkers.

Main Results:

• All SS and SSI scales demonstrated acceptable reliability.
• Anxiety, personality, and health scales exhibited strong psychometric properties.
• Chronic fatigue, coping, job satisfaction, and sleep scales showed weaker psychometric performance, suggesting areas for improvement.
• IRT analysis indicated overall adequacy but highlighted items needing alteration or omission.

Conclusions:

• The SS and SSI are generally reliable but require psychometric refinement, particularly for fatigue, coping, satisfaction, and sleep measures.
• Further validation in diverse populations is recommended due to reliance on a single sample.