Evaluation of the stress management intervention found that in the short term, the intervention was not effective in reducing the frequency or severity of daily hassles perceived by the participants, nor in increasing the frequency or severity of perceived uplifts in their lives relative to the control subjects.
Similarly, it was found that the stress management workshops were not effective in reducing the participants' levels of strain, in terms of their scores on the General Health Questionnaire. Following the intervention, there was no significant change in the experimental participants' scores, relative to the change in the control subjects' scores, on the somatic symptoms, anxiety and insomnia, social dysfunction and severe
depression scales of the GHQ-28 following the intervention. There was also found to be no significant change in the experimental participants' systolic and diastolic blood pressure scores following the intervention.
In terms of somatic complaints, the present study supported the findings of previous research by Ganster, Mayes, Sime and Tharp (1982), in which no significant changes were observed in the dependent variable over the period of the intervention. Similarly, the present research also supported Ganster et al's (1982) finding of no significant changes in the experimental participants' levels of anxiety over the period of the intervention.
However, other research has found significant reductions in the anxiety levels of
participants following a stress management intervention (Richardson, Beall and Jessop, 1983; Weisen, 1991; Hains, 1992). Differences between the findings from other studies, and those from the present research, may be explained by methodological differences. For example, Weisen's (1991) study was directed at a community sample, unlike the present research which was undertaken within an organisational context. Similarly, the research by Richardson et al (1983) and Hains (1992) were carried out on
groups of adolescents. Furthermore, in Weisen's (1991) study, the experimental and control subjects showed similar levels of anxiety prior to the intervention, unlike the present research in which the experimental participants scored significantly higher on the measure of anxiety than the control subjects. The author would argue that within the present study, the high levels of anxiety amongst the experimental participants meant that prolonged and intensive treatment would be required before any changes would be observed.
Clearly, it is difficult to make comparisons between the findings from one evaluative study with those from another, due to differences in the nature of the sample groups, and also differences in the design of the interventions. A programme which is found to be effective in reducing the levels of stress of a group of adolescent boys may not be effective within an organisational setting. Such differences therefore need to be taken into consideration when any comparisons between evaluative studies of stress
management interventions are being made.
The present research found no significant changes in the experimental participants' systolic and diastolic blood pressures following the stress management intervention. Previous research has suggested that reductions in blood pressure following an intervention may be limited to subjects with hypertension. In view of the fact that the majority of subjects in the present research were not hypertensive prior to the
intervention, the lack of a significant finding is not therefore surprising. However, even with groups of hypertensive subjects, research has suggested that reductions in blood pressure may be as a result of habituation to the measurement procedure, rather than to any specific effects caused by the intervention itself (Johnston et al, 1993). This should therefore be considered within future evaluative studies of stress management intervention, where blood pressure is used as the outcome measure. Habituation procedures should be incorporated into the design of the research, particularly where hypertensive subjects are involved.
Social dysfunction has not been used as an individual outcome measure in previous evaluative research, but it does appear to relate to the functioning at work variable which has previously been considered (Michie and Sandhus, 1994) The social
dysfunction factor from the GHQ-28 is a more global measure of functioning, unlike the scale used in the research by Michie and Sandhus (1994) which was specific to work situations. This may explain the differences in the findings between Michie and
Sandhus' (1994) study, in which significant increases in functioning at work were found amongst the experimental subjects, and the findings from the present research in which no significant changes in social functioning were observed. However, a number of flaws were present within the Michie and Sandhus (1994) research. The scale used to measure functioning at work consisted of a single item taken from a larger
questionnaire. Although the questionnaire had previously been validated, it may have been appropriate to have used a more extensive questionnaire which consisted of several items for each variable considered. A second criticism of the research by Michie and Sandhus (1994), is that only nine participants were involved in each of the experimental and control groups, compared with the sixty-five subjects used in the present research. The author would therefore argue that the differences in the findings between Michie and Sandhus' (1994) study and the present research is likely to be as much a result of methodological flaws in the former research as differences in the outcome variable.
The final factor of the General Health Questionnaire-28, severe depression, has been used as an outcome variable in many evaluative studies of stress management
interventions. The majority of the studies have found stress management programmes to be effective in reducing the levels of depression of experimental participants. (Sallis et al, 1987; Stiles, Shapiro and Firth-Cozens, 1988; Hains, 1992). However, in the present research, the reduction in the experimental participants' levels of severe
depression following the intervention was not statistically significant. It should be noted though that there was a tendency for the experimental participants' depression scores to be lower following the intervention, relative to the change in levels of depression
amongst the control subjects. Methodological differences between previous studies and the present research may have accounted for the lack of significant findings within the present research. For example, the research by Stiles, Shapiro and Firth-Cozens (1988) involved mainly depressed participants, who underwent a programme of eight sessions of stress management. However, within the present research, there was a high degree of variation in the levels of depression amongst the experimental group prior to the intervention (Mean = 5.79, a = 16.2). Differences in the nature of the stressors experienced by experimental groups of subjects from different evaluative studies may also have accounted for differences in the findings between previous studies and the present research. For example, the research by Antoni et al (1991) involved people who were being notified of their HIV-1 antibody status, a stressor which was considerably different to the stressors experienced by the participants in the
present research. Such differences between the participants, and the stressors experienced by them, must therefore be recognised when making comparisons between different evaluative studies.