Chapter 3: Research Philosophy and Methodology
3.5 The Exploratory case study
3.6.2 The Delphi Group (Embedded Explanatory Study)
The Delphi Technique in General
The Delphi technique is a widely used and accepted technique for gathering data from respondents within their field of expertise (Hsu and Sandford, 2007). According to Turoff (2002) the technique involves the setting up of a group of experts who are generally not known to each other and then to request them complete provide comments and estimates on a problem that is set by the study facilitator (Graefe and Armstrong, 2011). The survey is normally conducted by correspondence using a number of iterations. After each iteration the estimates and comments are summarised and sent back to the participants as feedback. The participants then revise their estimates etc. and return them as before. There may be up to four or five iterations with the final document representing an aggregation of the findings (Graefe and Armstrong, 2011). Seeing reliability is considered to be vital between cases in any multiple case study, replication in coding and framing of data is advisable (Yin, 2009). The RCA (Portwood and Reising, 2007) cause and effect approach was used as the framing tool and this is similar to axial coding based on functional similarities between the contextual issues and how these all relate to the study of stair descent.
The technique adopted
The objective of the proposed Delphi study was to:
“To correlate informed judgements in a topic spanning a wide range of disciplines”
This objective agrees with the purpose of Delphi group outcomes suggested by Hsu and Sandford (2007). The author developed a technique based on facilitated consensual opinion seeing this suited the RCA approach and still relied on the eliciting of the initial expert comments and estimates being carried out separately. The author was relying on a “tolerated” consensus i.e. one where
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the experts would agree not to delete certain opinions in the second round in a two-tier approach. Consensus is not totally ruled out by all experts on Delphi (Hsu and Sandford, 2007) so that a “tolerated” consensus was utilised.
A two-tier approach was used which involved the selection of a Delphi Group that comprised two sub-groups. The selection of group members was supposed to be based on one member not knowing the other (Turoff, 2002). This was a difficult requirement to comply with, given that the field comprises so few researchers. The US members did know each of each other. The UK members did not know one another and only one knew of the other. This was considered to be an even balance given the guidelines provided by Turoff (2002).
Figure 3-11: Explanatory study Delphi Group composition and process
US Expert 1
engineering science fire safety engineer – human behaviour specialist
US Expert 2
engineering science fire safety scientist and egress modeller
US Expert 3
engineering and health science ergonomist – stair safetyUK Expert 1
engineering science – environmental psychologyUK Expert 2
health science – bariatricsUK Expert 3
health science – biomechanics engineerUK Expert 4
engineering science – architectural stair safetyFacilitator
ROUNDS ONE & TWO 6 classifications
Experts critique US Ishikawa and suggest 4 classifications and reduced sub-categories US chart should form aid de memoire
The group was assembled as described in Figure 3-11 above. The group comprised two sub groups one located in the United States and the other in the United Kingdom. The experts are highly qualified in their field and all have published internationally in peer reviewed journals or have been part of an international research project connected with the problem. A summary of their curricula vitae may be found in the Appendix A3. The make-up of the group was as follows:
• The US Group members comprised one of the members of the original 1980 study expert group referred to under the Exploratory case study. The other two experts are involved in the post WTC 9/11 incident research programme at the National Institute of Standards and Technology (NIST) in the field of egress113.
• The UK Group complimented the US Group in terms of disciplines in terms of the objective of the Delphi Group study as noted in the first paragraph of this section (Hsu and Sandford, 2007) in terms of their multi-disciplinary backgrounds.114
Due to time constraints a facilitated “Nominal Meeting” (Graefe and Armstrong, 2011) approach was used to gather and challenge the opinion. The anonymity requirements (Turoff, 2002) between members was achieved by the two tiered approach with one sub-group being located in the US and the others in the UK. The author acted as a facilitator to the group and the conduct of the study followed the process summarised in Figure 3-11 producing the outcomes in line
113 US Group comprised Jake Pauls, Dr. Erica Kuligowski and Jason Averill.
114 UK group comprised Mike Roys of the Building Research Establishment being an expert Architect on stair safety, Dr. Neil Reeves, biomechanical engineer specialising in stair climbing from the Metropolitan University of Manchester, Dr. Patricia McDermott, Environmental Psychologist from the School of Sports Science, University of Loughborough and Anita Rush, Bariatric Health Care Consultant from the NHS who participate in the study of Hignett et al (2007) concerned with the movement of morbidly obese people.
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with Figure 3-12 below. Face to face interaction within the group was kept to a minimum especially so a dominant member would not take over the process with two facilitated meetings being held at different times representing a total of three rounds of the Policy Delphi technique (Turoff, 2002). The US Group met first in Gaithersburg, Maryland at the offices of NIST and the author acted as the facilitator. The brief was straightforward. An Ishikawa Chart (Ishikawa, 1982) with suggested classifications formed the questionnaire together with aim of the PhD Case Study. The instructions were to re-classify and then populate the context of individual stair descent performance in trial evacuations. A chart was handed to each member of the group and they completed the classifications. They returned the charts to the author who then circulated them with comments. The classifications were set at six as shown in Chapter 6. The charts were then handed out again and the members asked to populate each classification. On completion of this task the charts were circulated with a request whether or not there was anything further to be added. The facilitator then gathered up the charts and combined all the information on to one chart. This chart is “Outcome 1” as shown in Figure 3-12 below:
The UK sub-group was assembled at the University of Salford shortly after the completion of “Outcome 1” and each member supplied with a copy of the document, the PhD Case Study aim and a request to modify the chart according to their field of expertise. Once again the author acted as the facilitator. The facilitator allowed the session to be more open-ended and was asked questions by the members of the group for more detail about the aim. Following these questions the members and the facilitator decreased the number of classifications. This new chart was then modified and repopulated by the group. Many of the original factors remained but regrouped. This revised chart is “Outcome 2” (Figure 3-12).