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An introduction to the journal's supplement is presented in which the authors discuss the questionnaire referred to as "The Copenhagen Psychosocial Questionnaire," (COPSOQ), developed by Professor Tage Søndergård Kristensen.

Aims: To evaluate the construct validity of the Copenhagen Psychosocial Questionnaire II (COPSOQ II) by means of tests for differential item functioning (DIF) and differential item effect (DIE). Methods: We used a Danish general population postal survey (n=4,732 with 3,517 wage earners) with a one-year register based follow up for long-term sickness absence. DIF was evaluated against age, gender, education, social class, public/private sector employment, and job type using ordinal logistic regression. DIE was evaluated against job satisfaction and self-rated health (using ordinal logistic regression), against depressive symptoms, burnout, and stress (using multiple linear regression), and against long-term sick leave (using a proportional hazards model). We used a cross-validation approach to counter the risk of significant results due to multiple testing. Results: Out of 1,052 tests, we found 599 significant instances of DIF/DIE, 69 of which showed both practical and statistical significance across two independent samples. Most DIF occurred for job type (in 20 cases), while we found little DIF for age, gender, education, social class and sector. DIE seemed to pertain to particular items, which showed DIE in the same direction for several outcome variables. Discussion: The results allowed a preliminary identification of items that have a positive impact on construct validity and items that have negative impact on construct validity. These results can be used to develop better short form measures and to improve the conceptual framework, items and scales of the COPSOQ II. Conclusions: We conclude that tests of DIF and DIE are useful for evaluating construct validity. [ABSTRACT FROM AUTHOR]

Aims: Reliabilities of the work environment questionnaire Copenhagen Psychosocial Questionnaire (COPSOQ) have previously been estimated by Cronbach's alpha, but since the internal consistency assumption may not apply to all COPSOQ scales, Cronbach's alpha may underestimate true reliability. This study aims to evaluate reliability in a test--retest design. Methods: We analyzed postal questionnaire data from 349 persons (of whom 283 were employees) who completed two forms with a median interval of 22 (range 6-65) days between baseline and follow-up. Test--retest reliabilities were estimated by the intraclass correlation (ICC). For scales where the internal consistency assumption was theoretically plausible, reliabilities were also estimated by Cronbach's alpha and by Green's test--retest alpha. Results: With one exception, the ICC estimated reliabilities of the COPSOQ scales were adequate or good (range 0.70--0.89). A scale concerning mutual trust between employees had a low reliability of 0.64. Among the scales where the internal consistency assumption was plausible, Cronbach's alpha was adequate or good (0.75--0.85) for seven out of eight scales. Green's retest alpha was adequate or good for six out of eight scales (0.72--0.81). Conclusions: Standard criteria for acceptable intraclass correlation reliability were achieved for all COPSOQ scales but one. The test--retest design and intraclass correlation appears to be more appropriate than Cronbach's alpha for assessing the reliability of psychosocial work environment scales. [ABSTRACT FROM AUTHOR]

Aim: To determine minimally important differences (MIDs) for scales in the first version of the Copenhagen Psychosocial Questionnaire (COPSOQ). Methods: Data were taken from two separate studies: a national population survey (N=1062), and an intervention study at 14 workplaces (N=1505). On the basis of the population survey, the MID for each COPSOQ scale was calculated as one-half of a standard deviation (0.5 SD). For the core COPSOQ scales on "Quantitative demands", "Influence at work", "Predictability", "Social support (from colleagues and supervisors, respectively)", and "Job satisfaction", the MIDs were evaluated in the intervention study, where score differences for the scales were linked to the respondents' global self-evaluation of the impact of the interventions. The scales were scored from 0 to 100 in both studies. Results: The MIDs calculated as 0.5 SD were, on average, 9.2 (range 6.8-14.9) for the long version scales, and 10.8 (range 7.6-14.9) for the medium-length version scales. The analysis of the self-evaluated changes on the scale scores for the core COPSOQ scales showed that the anchor-based estimates of MID were generally lower than 0.5 SD. Conclusions: We recommend the following MID values for the COPSOQ scales: "Quantitative demands", 0.3 SD; "Influence", 0.2 SD; "Predictability", 0.3 SD; "Social support from colleagues", 0.3 SD; "Social support from supervisor", 0.7 SD; and "Job satisfaction", 0.4 SD. For all other COPSOQ scales, where we do not have anchor-based results, we recommend the conventional MID value of 0.5 SD. [ABSTRACT FROM AUTHOR]

Aims: The purpose of this study was to describe psychosocial work environment inequalities among wage earners in Spain and Denmark. Methods: Data came from the Spanish COPSOQ (ISTAS 21) and the Danish COPSOQ II surveys both performed in 2004-05 and based on national representative samples of employees with a 60% response rate. Study population was 3,359 Danish and 6,685 Spanish women and men. Only identical items from both surveys were included to construct 18 psychosocial scales. Socioeconomic status was categorized according to the European Socioeconomic Classification System. Analysis included ordinal logistic regression and multiple correspondence analysis after categorizing all scales. Results: A relationship between socioeconomic status and psychosocial work environment in both Denmark and Spain was observed, with wider social inequalities in Spain for many scales, describing a strong interaction effect between socioeconomic status and country. Conclusions: Socioeconomic status is related to psychosocial work environment and some adverse psychosocial conditions tend to cluster in lower socioeconomic status groups in both Spain and Denmark. This effect could be modified by a country's characteristics, such as economic and labour market structures, normative regulations and industrial relations including work organization. Hence, preventive strategies to reduce social inequalities in working conditions should consider the combination of actions at the macro and micro levels. [ABSTRACT FROM AUTHOR]

Aims: The aim of the present paper is to present the development of the second version of the Copenhagen Psychosocial Questionnaire (COPSOQ II). Methods: The development of COPSOQ II took place in five main steps: (1) We considered practical experience from the use of COPSOQ I, in particular feedback from workplace studies where the questionnaire had been used; (2) All scales concerning workplace factors in COPSOQ I were analyzed for differential item functioning (DIF) with regard to gender, age and occupational status; (3) A test version of COPSOQ II including new scales and items was developed and tested in a representative sample of working Danes between 20 and 59 years of age. In all, 3,517 Danish employees participated in the study. The overall response rate was 60.4%; (4) Based on psychometric analyses, the final questionnaire was developed; and (5) Criteria-related validity of the new scales was tested. Results: The development of COPSOQ II resulted in a questionnaire with 41 scales and 127 items. New scales on values at the workplace were introduced including scales on Trust, Justice and Social inclusiveness. Scales on Variation, Work pace, Recognition, Work-family conflicts and items on offensive behaviour were also added. New scales regarding health symptoms included: Burnout, Stress, Sleeping troubles and Depressive symptoms. In general, the new scales showed good criteria validity. All in all, 57% of the items of COPSOQ I were retained in COPSOQ II. Conclusions: The COPSOQI concept has been further developed and new validated scales have been included. [ABSTRACT FROM AUTHOR]