|Year : 2020 | Volume
| Issue : 3 | Page : 196-202
Demand–Control–Support Questionnaire: Psychometric characteristics and measurement invariance across gender and academic ranks among Nigerian University teachers
Olutayo Aloba1, Tolulope Opakunle2, Addah Tamuno3
1 Department of Mental Health, Obafemi Awolowo University, Ile-Ife, Osun State, Nigeria
2 Department of Mental Health, State Specialist Hospital, Osogbo, Osun State, Nigeria
3 Department of Psychology, Obafemi Awolowo University, Ile-Ife, Osun State, Nigeria
|Date of Submission||13-Aug-2019|
|Date of Decision||06-Feb-2020|
|Date of Acceptance||20-Mar-2020|
|Date of Web Publication||28-Sep-2020|
Dr. Olutayo Aloba
Department of Mental Health, Obafemi Awolowo University, Ile-Ife, Osun State
Source of Support: None, Conflict of Interest: None
Background: No occupational stress-related instrument has been psychometrically examined among Nigerian university teachers. Aim: This study examined the 17-item Demand–Control–Support Questionnaire (DCSQ-17) in terms of factor structure, reliability, validity, and measurement invariance across gender and academic ranks among Nigerian university teachers (n = 597) from a federal institution in Southwestern Nigeria. Materials and Methods: They completed the DCSQ-17, in addition to the Maslach Burnout Inventory (MBI), and the Zung Self-Rating Anxiety Scale (ZSAS). Results: The original DCSQ-17 three-dimensional model (demands, control, and support) was affirmed with confirmatory factor analysis. There was evidence to support the configural, metric, and scalar invariances across genders and academic ranks. The reliability coefficients (McDonald's omega) of the subscales were satisfactory. Criterion validity was supported through correlational analyses with the MBI and ZSAS. Conclusion: The DCSQ-17 is useful as a stress evaluation instrument among Nigerian university teachers. Further studies are needed to confirm the psychometric properties among other Nigerian occupational groups.
Keywords: Demand–Control–Support Questionnaire, factor structure, measurement invariance, Nigerian university teachers, reliability, validity
|How to cite this article:|
Aloba O, Opakunle T, Tamuno A. Demand–Control–Support Questionnaire: Psychometric characteristics and measurement invariance across gender and academic ranks among Nigerian University teachers. Indian J Soc Psychiatry 2020;36:196-202
|How to cite this URL:|
Aloba O, Opakunle T, Tamuno A. Demand–Control–Support Questionnaire: Psychometric characteristics and measurement invariance across gender and academic ranks among Nigerian University teachers. Indian J Soc Psychiatry [serial online] 2020 [cited 2023 Feb 6];36:196-202. Available from: https://www.indjsp.org/text.asp?2020/36/3/196/296265
| Introduction|| |
Job-related stress constitutes a significant burden on subjective health and well-being. Approximately 25% of all workers are affected by job-related stress, and almost 60% of the days an individual was unable to work could be attributed to occupational stress. Recent studies among university teachers reported increasingly complex working conditions, and a significant proportion indicated an increasingly stressful perception of their job role. It has been reported that teaching at the university level as a profession is specifically associated with elevated stress. Factors that have been identified as contributing to the high level of stress among the university academic staff include rapid decision-making, achieving equilibrium between the expectations from, and interpersonal relationships with junior and senior colleagues and students. Additional factors include pressures from regular assessments for promotions and evaluation of job performance. A cross-sectional national Australian study of almost 9000 respondents from 17 universities reported that a significant proportion of teachers (43%), compared to nonteachers (37%), had experienced significant levels of stress related to their jobs. Job-related stress among teachers has been reported to significantly contribute to the development of psychological and physical health problems and early retirement in developed countries, in addition to an increased incidence of burnout. Occupational related stress has a positive correlation with burnout and a negative correlation with job satisfaction among teachers.
Few studies have examined stress and its correlates among Nigerian university teachers. A major methodological limitation with available studies is that stress was evaluated with arbitrarily formulated study-specific questionnaires of unknown validity and reliability. None of these studies utilized a stress-evaluating questionnaire that has been demonstrated to possess satisfactory psychometric properties or measurement invariance (MI) in relation to gender and academic rank among Nigerian university teachers. Thus, the results reported by the previous Nigerian authors need to be interpreted with caution. One problem with the validation of an occupational stress tool among Nigerian university teachers is that there are no previously validated instruments which evaluate a similar construct, against which the 17-item Demand–Control–Support Questionnaire (DCSQ-17) can be examined. The availability of such a tool would have enabled the examination of the concurrent validity of the DCSQ-17.
The demand–control model of job stress was initially proposed by Karasek, who indicated that occupational stress results from a combination of elevated psychological demands and low job control, also referred to as decision latitude. The third component (work-related social support) was later added. Evaluating teachers' work-related stress with psychometrically valid and reliable instruments can positively contribute to their health care through the provision of information that can influence educational policymaking. We chose the 17-item DCSQ. as it is brief to administer and is available free of cost. This study aims to evaluate the psychometric properties of the DCSQ-17 in a sample of Nigerian university teachers. Specifically, we examined the factor structure of the 17-item DCSQ, in addition to its criterion validity and reliability. We also evaluated the MI of the questionnaire across genders and the junior and senior academic ranks.
| Materials and Methods|| |
Participants and procedure
This was a cross-sectional study that was conducted at Obafemi Awolowo University in Southwestern Nigeria between February 2019 and May 2019. The university has 13 faculties spanning the arts, humanities, engineering, sciences, law, social sciences, administration, health sciences, agricultural sciences, and pharmacy. A research packet for self-completion was distributed to 700 teachers across faculties through their mailboxes. This packet included a document explaining the purpose of the study, a consent form, and the study measures. The teachers were to anonymously complete the study measures and place them in their mailboxes for retrieval by the authors. Eighty-four of them returned incompletely filled study measures, whereas 19 refused to give consent. Thus, data for analysis were available from 597 teachers (response rate of 85.3%). Ethical approval for the study was obtained from the Ethics and Research Committee of the university.
Sociodemographic and academic variable questionnaire
This contained details such as age, gender, and academic level (graduate assistant, lecturer I, lecturer II, senior lecturer, associate professor, and professor). The junior rank comprises those who were graduate assistants and those in lecturer I and II positions.
17-item Demand–Control–Support Questionnaire
This is a 17-item self-completed scale to quantify employees' perception of the demands, control/decision latitude, and social support associated with their jobs. It was developed based on the three-dimensional approaches of demand, control/decision latitude, and social support to work-related stress. The DCSQ-17 was extracted from the much longer 49-item Job Content Questionnaire (JCQ) which quantifies job-related stress on 6 dimensions including psychological demands, decision latitude (control), work-related social support and other occupational characteristics including physical demands, macro-level decision authority, and job insecurity. The demand subscale of the DCSQ-17 consists of 5 items rated on a 4-point Likert scale, ranging from “often” to “never/almost never.” Items on this subscale quantitatively evaluate work stress-related psychological pressure such as the time, effort, and speed required to achieve a task. The DCSQ-17 control or decision latitude subscale is comprised of 6 items which are similarly rated as the demand subscale. These 6 items quantitatively assess the extent which the worker can engage his or her cognitive abilities in the execution of occupational-related tasks and the degree of the autonomy the worker has in making decisions about how to execute such tasks. Extensive research has demonstrated that a job atmosphere characterized by increased job demands and reduced job-related control is associated with deleterious physical and mental health outcomes. The item that enquires about having enough time on the subscale and the one that inquired about repetitiveness at work on the control/decision latitude subscale are reversed scored (1–4). The third dimension (social support subscale) evaluates the level of work-related social support and consists of 6 items that quantitatively measures the social relationship between the worker and other colleagues. Each item on this subscale is rated on a 4-point Likert scale, from “strongly agree” to “strongly disagree.” Sample items included: “Do you have to work very fast?” (job demands), “Do you have a choice in deciding how you do your work?” (control/decision latitude), and “My co-worker supports me” (social support). The three subscales of the DCSQ-17 (demand, control, and support) are not independent and are used together to quantitatively evaluate the three dimensions of work-related stress. The response to the items is summed up to yield to an aggregate score for each of the three subscales.
Maslach Burnout Inventory
The phenomenon of burnout among the study population was evaluated with the 22-item self-completed Maslach Burnout Inventory (MBI), which consisted of three subscales: Emotional Exhaustion (EE) – 9 items, Depersonalization (Dep) – 5 items, and Personal Accomplishment (PA) – 8 items. Each item is rated on a frequency scale from 0 (never) to 6 (every day). Burnout is indicated by higher scores on the EE and Dep subscales and lower scores on the PA subscale. We included the MBI in the present study as studies from developed countries reported that occupational stress among teachers is strongly associated with burnout., Burnout is indicated by higher scores on the MBI-EE and MBI-Dep subscales and lower scores in the MBI-PA subscale. The MBI has been demonstrated to possess adequate reliability and validity among different categories of Nigerian workers.
Zung Self-Rating Anxiety Scale
The level of subjective anxiety was assessed with the 20-item Zung Self-Rating Anxiety Scale (ZSAS), which evaluates anxiety symptoms on four dimensions: cognitive, autonomic, motor, and central nervous system. Each item is scored on a 4-point Likert-type scale (1–4). Anxiety symptoms were assessed among our respondents because previous studies from developed countries have demonstrated a significant positive correlation with occupational stress among teachers. Satisfactory psychometric characteristics of the ZSAS have been reported among the Nigerian general population.
This was conducted with the 21st version of the Statistical Package for Social Sciences (SPSS) and R Psych Package (IBM, Illinois, Chicago, USA). CFA was performed with the 20th version of the SPSS Analysis of Moment Structure software (IBM, Illinois, Chicago, USA) using the maximum likelihood estimation with covariance matrix input method to affirm the three-factor model of the DCSQ-17. We evaluated the fit adequacy of our data with the following indices: significance of the ratio of the Chi-square (χ2) and its associated degree of freedom (χ2/df), the comparative fit index (CFI), the root mean square error of approximation (RMSEA), and the standardized root mean square residual (SRMR). The main limitation of the significance (P value should exceed 0.50) of the χ2/df ratio (which should be less than 3.0) is its sensitivity to sample size, which invariably tends to produce a significant P value when the sample is large, thereby erroneously rejecting the proposed model. We, therefore, focused on the CFI, RMSEA, and SRMR values. A generally accepted cutoff that lends credence to the acceptability of data to model fit is a CFI value of 0.90. Furthermore, an acceptable model fit is indicated by RMSEA and SRMR values between 0.06 and 0.08, whereas values below 0.06 affirm an excellent model fit., We examined the criterion validity with correlational analyses (Pearson's product-moment correlations) with the MBI and the ZSAS. The reliabilities of the DCSQ subscales were evaluated with the McDonald's omega (ω) values instead of the traditional Cronbach's alpha (α), which tends to overestimate or underestimate the reliability of a scale's items. Afterward, we evaluated the gender and academic rank MIs. Before similarities and differences in the same construct across different groups can be compared, item factor loadings and intercepts must be equivalent (invariant) across these groups. A statistical tool that has facilitated the comparison of group differences in relation to MI is multigroup CFA.
Tests of measurement invariance across genders and academic ranks
Confirmatory factor analysis
This was conducted separately for gender and those in the junior and senior academic ranks. Our data must demonstrate a satisfactory fit separately for gender and academic ranks. This is the first step toward the establishment of MI.
At this level, all the parameters of the model will be estimated freely across gender and academic ranks. The loading of the same observed variables (DCSQ-17 items) on the same constructs (DCSQ-17 subscales) must be equivalently demonstrated by gender and academic ranks. The item loadings must be significant, and the three subscales should have correlations below 1. This level of MI indicates that across gender and academic rank, the three factors of the DCSQ-17 are similar. Configural MI does not indicate that there is actual MI.
At this level of MI, all the factor loadings (DCSQ-17 subscales) of the same observed variables (DCSQ-17 items) must be equivalent across genders and academic ranks. The establishment of metric MI means that the male and female lecturers and those in the junior and senior academic ranks interpreted the 17 items of the DCSQ in like manners. Metric invariance is a prerequisite for the comparison of correlates of factors across groups. It is assessed by imposing equal restrictions on the factor loadings between the DCSQ-17 items and subscales across gender and academic ranks.
This must be established before the means of constructs (DCSQ-17 subscales) can be compared across groups. The confirmation of scalar invariance means that the male and female teachers and those in the junior and senior academic ranks adopted a similar response format to the DCSQ-17 items and subscales. Fulfillment of scalar MI means that any differences in relation to the 17 items of the DCSQ are not as a result of factors such as gender or academic rank bias. Scalar MI is assessed by equivalently placing constraints on the factor loadings (as performed in metric MI), and the item intercepts across the groups. Gender and academic rank MI establishment for the DCSQ-17 was based on the alterations in the CFI (ΔCFI), RMSEA (ΔRMSEA), and SRMR (ΔSRMR) values. Metric invariance is confirmed by Δ CFI ≤−0.01, ΔRMSEA ≤0.015, and Δ SRMR ≤0.03 compared to the configural model, whereas scalar invariance is indicated by Δ CFI ≤−0.01, ΔRMSEA ≤0.015, and Δ SRMR ≤0.01 compared to the metric model.
| Results|| |
As shown in [Table 1], there were 368 (61.5%) male teachers. The mean age was 42.34 (standard deviation: 9.58). Furthermore, the mean scores on the DCSQ-17 subscales, the MBI, and the ZSAS are shown in [Table 1]. [Table 2] shows that there were significant correlations between the DCSQ-17 subscales and some of the other study measures. The DCSQ-Demand subscale had a modest negative correlation with MBI-PA subscale (r = −0.088, P < 0.05) and a modest positive correlation with ZSAS (r = 0.150, P < 0.001). The DCSQ-Control subscale had modest negative correlations with the MBI-Dep subscale (r = −0.094, P < 0.05) and ZSAS (r = −0.198, P < 0.001), whereas the DCSQ-Support subscale had negative correlations with the MBI-EE subscale (r = −0.262, P < 0.001), the MBI-Dep subscale (r = −0.188, P < 0.001), and the ZSAS (r = −0.403, P < 0.001) and positive correlations with the MBI-PA subscale (r = 0.101, P < 0.05). There were modest intercorrelations among the DCSQ subscales (r = 0.111–0.497). [Table 2] also shows the omega reliability coefficient values (ω) of the three DCSQ subscales. The three subscales of the DCSQ-17 have satisfactory reliabilities. The CFA path diagram and the item loadings of the three DCSQ subscales are depicted in [Figure 1]. All the model fit indices were acceptable.
|Table 1: Sociodemographic and study measurement characteristics of the respondents (n=597)|
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|Table 2: Correlation (Pearson's) between the 17-item Demand-Control-Support Questionnaire subscales and other study measures|
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|Figure 1: Confirmatory factor analysis path diagram depicting the item loadings on the original Demand–Control–Support Questionnaire (n = 597); indices of model fit-χ2/df = 2.812, comparative fit index = 0.951, standardized root mean square residual = 0.0436, root mean square error of approximation = 0.055/90% confidence interval = 0.048–0.063|
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[Table 3] shows that among the male teachers, the DCSQ-17 exhibited acceptable model fit indices in relation to the CFI, SRMR, and RMSEA values. Among the males, the item loadings on the demand subscale ranged from 0.48 to 0.79, control subscale item loadings ranged from 0.47 to 0.86, whereas on the social support subscale, item loadings ranged from 0.51 to 0.79. Among the males, the correlations among the three subscales ranged from 0.17 to 0.69. Among the female respondents, the values of the CFI, SRMR and RMSEA were all acceptable. The loadings of the items on the demand subscale ranged from 0.45 to 0.84, while the item loadings on the control subscale ranged from 0.54 to 0.75. Among the female respondents, item loadings on the social support subscale ranged from 0.50 to 0.76. Among the females, the correlations among the three factors ranged from 0.28 to 0.80. [Table 3] also shows that the configural gender MI for the three-factor DCSQ-17 model had acceptable fit indices. Subsequently, a metric MI in relation to the genders also exhibited satisfactory fit indices. Likewise, a scalar MI after the imposition of item intercept equality for both genders yielded acceptable model fit indices. The changes in the CFI, SRMR, and RMSEA values between the metric and scalar models all supported gender MI for the three-factor DCSQ-17. Furthermore, as depicted in [Table 3], among those in the junior academic rank, the DCSQ-17 exhibited acceptable model fit indices as regards the CFI, SRMR, and RMSEA values. Among the junior cadre rank, the item loadings on the Demand subscale ranged from 0.54 to 0.82, Control subscale item loadings ranged from 0.48 to 0.89, whereas on the Social support subscale, item loadings ranged from 0.52 to 0.74. Among those in the junior rank, the correlations among the three subscales ranged from 0.23 to 0.73. Among the respondents in the senior academic rank the values of the CFI, SRMR and RMSEA were all acceptable. The loadings of the items on the Demand subscale ranged from 0.44 to 0.78, while the item loadings on the Control subscale ranged from 0.52 to 0.87. Among the respondents in the senior academic rank, item loadings on the Social support subscale ranged from 0.45 to 0.91. Among the senior academic rank members, the correlations among the three factors ranged from 0.20 to 0.72. As shown in [Table 3], the configural academic rank MI for the three-factor DCSQ-17 model had acceptable fit indices. Likewise, a metric MI in relation to the academic rank also demonstrated acceptable fit indices. A scalar MI after the imposition of item intercept equality for both academic ranks yielded acceptable model fit indices. The alterations in the CFI, SRMR, and RMSEA values between the metric and scalar models in relation to the academic rank confirmed the MI of the DCSQ-17.
|Table 3: Test of gender and academic rank measurement invariances for the 17-item Demand-Control-Support Questionnaire among the university teachers|
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| Discussion|| |
In this study, we explored the psychometric characteristics of the original 17-item DCSQ in terms of its validity and reliability in a cross-sectional sample of Nigerian university teachers. We also applied CFA to affirm the previously established factor structure of the DCSQ-17. In addition, we evaluated the MI of the DCSQ-17 across the respondents' genders and academic ranks. The DCSQ-17 has fewer items than the JCQ from which it was extracted; thus, its usage as an occupational stress-evaluating tool is helpful in the context of jobs characterized by time constraints such as university academic work. In this study, we established the adequacy of the reliability of the DCSQ-17 subscales in our sample. To the knowledge of the authors, all the previous studies that examined the reliability of the DCSQ-17 subscales applied the Cronbach's α despite its shortcomings., In these studies, the Cronbach's α values ranged from 0.68 to 0.75, 0.50–0.77, and 0.77–0.84, respectively, for the demand, control/decision latitude, and support subscales. We noted that compared to what has been reported in the literature regarding the reliability (α) values of the three subscales, the ω values of these subscales in our study were relatively higher. Therefore, we can modestly conclude that the three DCSQ-17 subscales are reliable measures of occupation-related stress among our sample of Nigerian university teachers.
A number of psychological variables have been empirically correlated with the construct of job-related stress, such as burnout  and anxiety. In this study, we noted that the directions and strengths, though modest, of the correlations between the DCSQ-17 subscales and the measure of anxiety levels (ZSAS) were all statistically significant. Higher job demands correlated positively with higher anxiety, whereas higher job control and social support correlated negatively with anxiety. Although the three subscales did not significantly correlate with all the three dimensions of the MBI, we noted that higher demand was associated with reduced PA (MBI-PA) which indicated higher levels of burnout. In addition, higher job control and social support scores correlated with lower depersonalization (indicative of less burnout). Higher job social support was associated with lower EE (i.e., lower burnout). Therefore, based on these correlations, we can tentatively affirm that the DCSQ-17 subscales have, exhibited satisfactory criterion validity.
Applying CFA, we were able to demonstrate that our data exhibited a satisfactory fit to the original demand–control–support factor model. The CFA path diagram [Figure 1] depicts a model with satisfactory fit with regard to all its indices. It has been recommended that the SRMR should be reported with other indicators of model fit such as the CFI and RMSEA. In our study, the item loadings on each of the three subscales were modestly high (0.51–0.80). The social support subscale items demonstrated relatively high loadings, an observation that is in keeping with what was reported among a Swedish sample. The relatively lower loadings of the “Conflicting demand” item on the Demand subscale and the “Do the same thing over and over” item on the Control subscale were also been reported among Swedish  and Brazilian  samples.
A sound methodological approach for the comparison of job-related stress between the Nigerian male and female university teachers, and those in the junior and senior academic ranks, requires an instrument that demonstrates MI across these groups. The confirmation of gender and academic rank MIs for the DCSQ-17 means that any differences observed in relation to these categories are not due to a bias in response to items by males or females, or the junior or senior academic workers. The establishment of MI indicates that both males and females and those in the junior and academic ranks had equivalent responses to the DCSQ-17 in terms of its items and three subscales. Further analysis showed that there were no statistically significant differences in the three subscales in relation to the genders and academic ranks in our sample.
Our study has following limitations. First, our data were cross-sectional in nature, which disallowed us from testing the longitudinal stability of the DCSQ-17. Second, we recruited our sample from a university in only one of the six geopolitical regions of the country, thereby limiting the generalization of our findings to university academic workers in the other regions. Third, the healthy worker influence was not eliminated, i.e., the academic workers who were not healthy enough and were not available to participate in this study. This limitation was also highlighted in a validity study of the DCSQ-17 in Switzerland and the United States. Finally, our sample size was rather modest. The main strength of our study is that it is the first study in Nigeria and Sub-Sahara Africa to examine the validity, reliability, and confirmatory factorial structure of the DCSQ-17 among university academic workers. One other strength is that this is the first study to prove the invariance of the DCSQ-17 across genders and academic ranks among Nigerian university teachers.
| Conclusion|| |
We have provided preliminary evidence to support the structure of the demand–control–support model of work-related stress , among Nigerian university teachers. More studies involving extensive varieties of occupational groups are needed among the Nigerian population to further establish the psychometric adequacy and stability of the DCSQ-17. The DCSQ-17 appears to be useful as an instrument to quantitatively evaluate occupational-related stress among Nigerian university teachers.
We are sincerely grateful to the university teachers who agreed to participate in this study.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]