MICHAEL DEMPSEY - Cranfield University

• External validity: establishing the domain to which a study’s
findings can be generalised
• Reliability: demonstrating that the operations of the study can
be replicated.
On the first of these tests, Yin suggests(1994:34) (inter alia) two
strategies; multiple sources of evidence and to establish a chain of
evidence. On the first of these, documentary evidence has been used
as a means of giving fresh consideration to the conclusions from the
interview data. On the second, the use of the package QSR NVivo (see
below) for data analysis has enabled chains of evidence to be
discerned and audited throughout the project. The extent to which
causal relationships flow from the data will also be discernible from that
source, addressing the issue of internal validity. Reliability can be
demonstrated by the audit trail of the study; its structure, explained
herein, the interview aide-memoire, transcripts and the computer based
analysis.
External validity is addressed by the use of replication logic in this
multiple case design. Yin (1994:46) suggests that such studies should
follow a replication logic. Each case, he says, should be selected so
that it either ‘(a) predicts similar results (a literal replication) or (b)
produces contrasting results (a theoretical replication). Case study
subjects have been chosen for contrasting reasons, so that, if there are
contrasting results, these can be identified. The theoretical framework,
however, suggests literal replication. In the event that theoretical
replication occurs, this will have the effect of modifying the theoretical
framework. This is recognised by Yin who says that ‘if some of the
empirical cases do not work as predicted, modification must be made
to the theory.’
The conclusion presented here, therefore, is that a multiple case study
design for this research, with in case and cross case analysis, is an
appropriate design for the study of managerial activities within trade
unions which have merged.
3.4. CASES AND INTERVIEWEES
The case study unions have been described in Chapter 1, as has the
reason why the decision was taken to choose unions which had
merged. In the light of this decision, the choice of unions needed to
reflect a range of characteristics – particularly white collar, blue collar,
public sector and private sector.
When the choice was first being considered, in 1998, the most
significant mergers in the previous few years were the AEEU and
UNISON. A preliminary interview was held with a senior official of the
AEEU to sound out the possibility of access. Whilst this was a highly
amenable discussion, it was fairly clear that senior officials would be
likely to be unwilling to co-operate with anything like the candour which
64