Selection of cases

In the literature there is little consensus on what would be an appropriate number of cases when adopting a multiple case study approach. Eisenhardt (1989a) recommends that the number of cases should be between four and ten. The literature on case study sample size indicates that four cases should be the lower limit (Eisenhardt 1989a) since any less would create difficulty in generating theory with complexity. Miles and Huberman (1994) suggest that more than 15 cases can become unwieldy when dealing with high complexity. Multiple cases are a powerful means to create theory because they permit replication and extension among individual cases (Eisenhardt, 1991). By examining a number of cases, the researcher is able to enquire into events and behaviour in several organisations and gradually test and form theoretical constructs (Leonard and McAdam 2001). The case study method allows the development of theory through comparison; i.e. looking at the same event or process in

different settings or situations (Sitter et al. 1997). Seven companies that encompassed eight WLDs were studied to provide for meaningful analysis and comparison.

As usually happens in case study research (Yin 2003, Eisenhardt 1989a) the choice of the research sample is not random. In this research the population was limited to those companies that could be identified as having moved or opened a new facility over the two-year period, 2003 - 2005. Within the cases identified it was proposed that purposive sampling be used. This form of sampling uses the judgment of an expert in selecting cases or it selects cases with a specific purpose in mind (Babbie, 1998; Neuman, 2000). As Neuman (2000) noted, purposive sampling is appropriate in three situations. First, it is to select unique cases that are especially informative. Second, it is used to select members of a difficult-to reach, specialised population. Third, it is used to identify particular types of cases for in-depth investigation.

This sampling method is particularly suitable for this research for two reasons. Firstly interviewees are executives of selected firms who are relatively difficult to reach through alternative means and secondly the cases that were selected for study cover a range firms that are generally representative of the overall transport industry in Victoria. Additionally the two year time period was chosen to ensure that access to the staff who were involved in the decision making were still available and that the memory and recollections of the WLD process was still current in the minds of the senior management of the companies.

Details of companies that had either changed their location or established a new facility was sought from two separate sources; real estate transaction databases and the Melbourne telephone business directory. The real estate databases provided details of companies that had changed or developed new locations within the previous two years. This data was obtained from either new leases signed or properties that had been sold to transport companies. An examination of the Melbourne telephone business directory (The Yellow Pages) for 2003 and 2005 in the categories

Transport Services and Warehousing identified transport companies that had either moved or established a new warehouse in the intervening period.

The data from the two sources was then classified into geographical regions around Melbourne. It was obvious that there were three distinct geographical clusters where transport companies had re-located. The first cluster was in Melbourne’s south-eastern suburbs around Dandenong, the second cluster to the north of Melbourne around Campbellfield, and the last cluster to the south-west of Melbourne around Laverton and Altona. A map showing these general areas can be seen at Appendix A.

In total 29 companies were identified that had changed location within the two-year time span referred to above. Nine of these companies were considered specialist in nature (refrigerated goods, grain handling and wool carting) and these were excluded from the sample as discussed earlier in Section 1.8, (p13).

In selecting the companies for the case studies it was necessary to consider a range of firms in the transport industry. In selecting firms to be approached the size of the company, the ownership and management structure, the sophistication of the management of the company and individual management styles were all considered. In order to obtain a variety of cases to study 13 companies were selected from the remaining 20 companies. The companies were grouped according to size and geographical coverage. The geographical coverage was split into national, multi-state operations and local only operations and a deliberate strategy was to ensure that there were companies from each grouping in the research. It can be seen from Table 6.1 that there were three cases (B, C1 & C2) from national firms, three cases (A, D & F) from firms with operations in multiple (but not all States of Australia) and two cases (E & G) from firms that only have operations in Victoria.

Introductions to these companies were sought via the Chartered Institute of Transport or the Supply Chain and Logistics Association of Australia for

access to senior executives of the selected companies. In addition the researcher undertook ‘cold calling’ where an appropriate introduction could not be arranged. Of the 13 companies approached, six companies declined to participate in the research project. In the companies who declined to participate in the project were one national firm, two firms with multi-state operations and three firms who only operate in Victoria. The selection of cases was limited by the willingness of companies to disclose information relating to decision processes and current strategy.

As the identified population for this project was relatively small it was considered that a postal questionnaire would not have provided a greater response rate than the 35% achieved with the case studies.