Evaluating organizational stress-management interventions using ...

30 RANDALL, GRIFFITHS, COX
ward’’ (0 = ‘‘No’’, 1 = ‘‘Yes’’). These data were triangulated. Senior
managers (n = 4) were asked to identify wards which had received new
computer equipment. Documents detailing the progress of the installation
programme were also examined.
Analysis
A two-stage analytical procedure was used in both studies. First, the initial
pre – post design (assuming 100% exposure) was used. Each intervention
was evaluated through inspection of descriptive data and the use of pair
sampled t-tests and repeated measures ANOVAs to examine changes in
well-being over time. Covariates were not considered to allow for more
liberal testing of intervention effects thus reducing the chance of Type II
error. Traditionally this design would be used to test for the impact of the
intervention assuming 100% exposure.
In the second stage of analysis, exposure to the intervention was included
as a design variable. A repeated measures ANCOVA was used with one
between-subject variable (‘‘exposed’’ to the intervention or ‘‘not exposed’’ to
the intervention) and one within-subject variable (time) with two measurement
levels (Time 1 and Time 2). Covariates (age and length of service) were
included because of their potential influence over growth in the dependent
variable and to control for nonequivalence in the between-group portion of
the design and reduce the chance of Type I error (Cook & Campbell, 1979;
Tabachnick & Fiddell, 2001). The impact of exposure to the intervention
was assessed by examining the significance of the two-way interaction term
Intervention exposure 6 Time. Interaction effects were then explored in two
ways. First, paired sample t-tests were used to test for changes in exhaustion
scores within each group. Second, comparisons between the exposed and not
exposed groups were also made at both Time 1 and Time 2 using ANOVAs.
RESULTS
Study 1
Exposure to the intervention. The measure of awareness of the
intervention showed that most (25 supervisors) reported that they had been
made aware that they had regained control of fault reporting and repair
authorization. However, a significant proportion (32%) was not aware of
the change. There were no significant differences between the ‘‘aware/
exposed to the intervention’’ and the ‘‘not aware/not exposed to the
intervention’’ group in terms of demographic details (age, length of service,
the size of station they were based at), nor their exhaustion scores at Time 1,