Internal and External Validity: Operationalising the Case Study from Data to Theory

becomes necessary to explore the practical issues of validity associated with the mixed method approach taken as a route, to operationalise the case study from data to theory. This is because case study research can be associated with both quantitative and qualitative researches (Bryman, 1989). Typically, case studies in most organisational settings are carried out from an interpretivist or positivist viewpoint on the philosophical spectrum (Sexton, 2007). In the context of organisational research, Bryman (1989:25) distinguished qualitative case studies from quantitative case studies in terms of the “level of emphasis on interpretations of individuals working in the organisations”. Bryman (1989:26) stated that for qualitative case studies: “The research process often starts with a set of loose concepts, ideas and relationships

between issues perceived as relevant and important in relation to the knowledge domain based on the investigators preoccupation ... with theoretical reflections filling in the gaps during data collection”.

Quantitative case studies however, model the research process to closely mimic a scientific approach in which data on organisational attributes is collected and analysed with researcher’s impersonal detachment typical of experimental or survey research to establish verifiable facts (Bryman, 1989). Typical of a positivist approach, hypotheses are formulated, based on which statistical tests are carried out on numerical measures of the organisation. A positivist approach to theory construction in organisational studies, according to Bryman (1989) thus requires that all efforts are usually directed towards:

 Generating quantifiable attributes (Variables) to test the hypothesis;

 Establishing and demonstrating causality (Theoretical explanations/ Internal validity);  Ensuring generalization beyond the specific confines of the specific context (External

validity);

 Achieving replication/reliability (minimising the impact of researcher’s biases/values on credibility of research outcome).

Following this line of logic, and in tune with the critical realist philosophical underpinning of this research, the case study approach used to generate theory in this study, is a hybrid merger of the requirements of both qualitative and quantitative research. Theory in this case study, which assumes a critical realist orientation, is therefore generated qualitatively and quantitatively. Theory on Embedded Unit of Analysis 1 (how deltaic ground conditions induces cost overruns) is generated quantitatively, while theory on Embedded Unit of Analysis 2 (linking geotechnical practices in organisations to the high level of recorded cost overruns) is generated qualitatively. Figure 4.9 shows the researchers approach to data generation and triangulation of sources leading to theory construction.

Figure 4.9: Practical Approach to Theory Construction in this Study

This research starts from a prior set of concerns derived from the theoretical issues in the literature. Quantitative and textual data are then collected using semi-structured interviews and

Embedded Unit of Analysis 2 Qualitative Data Collection (Interviews on organisational design and

estimating practices) Embedded Unit of Analysis 1

Quantitative Data Collection (Spatial geotechnical index data and

archival project data)

Geo-Statistical Quantitative Data Analysis (Level-1 Theory)

Triangulation

Deductive/Inductive Qualitative Data Analysis

(Level-1 Theories)

Theory Generation (Level-2 Theory) Literature Review:

Background to highway development in the Niger Delta Critical Analysis of explanations to cost overruns

Inferential Literature:

Geo-Spatial literature on Niger Delta soils

Inferential Literature: Geotechnical best practices

documentary/archival sources. The incorporation of data from multiple sources is designed to improve the internal validity of the case study design, in terms of ensuring that premature conclusions are not drawn from circumstantial evidence, and the external validity of the study output. Dainty et al. (1997) advocated for triangulation of data to give different but convergent perspectives to the theoretical explanation of the phenomena under investigation. Dainty et al. (1997) explicitly rationalised this need on the following grounds:

 The systematic combination of different methods and data types reduces the possibility of the researcher drawing erroneous premature conclusion through an over-reliance on a single data set or technique;

 Increased generalisability of theories generated from social negotiation to having a wider resonance in the body of knowledge;

 Not being bounded by the empirical parameters of a study;

 Enhanced understanding of the study phenomena based on the holistic consideration of the various strands linking the evidence from various levels of enquiry.

The researcher’s approach to theory building follows the prescription of Yin (2014), whereby level-1 inferences, which are lower order theories generated from the different multiple sources, corroborate each other to yield a level-2 inference, which is an analytically generalizable theory, at a conceptual level higher than the case studied. This study in achieving triangulation, therefore:

 Generates a first Level-1 theory, by collecting numerical data on the spatially dispersed geotechnical index variables on subgrade soils at project locations, and cost overrun trends from archives. These are analysed geo-statistically in a quasi-experimental fashion, as an exploratory step to understand the inherent propensity for the deltaic ground conditions at project sites to induce cost overruns in highway projects. the findings from this phase builds up and links to further understanding what latent triggers exists in practice;

 Generates a second Level-1 theory, by collecting textual data on the geotechnical practices of the highway agencies during design and costing processes, with respect to managing risks due to the deltaic ground conditions at project sites. The qualitative data is deductively analysed, relative to standards of geotechnical best practice, to gain a

further in-depth understanding of the underlying issues accounting for the inference made from the preliminary geo-statistical analysis;

 Generates a third level-2 theory, in reflexive adaptation to unanticipated social constructs emerging from the qualitative data. Theory in this regard is thus further generated from the qualitative data using a purely inductive approach, similar to the approach of grounded theorising.

 Triangulates all the level-1 theories from the quantitative and qualitative strands of the case study to yield two ‘level-2 theories: A Regression Model explicitly accounting for the variance in cost overruns induced by geotechnical pathogens; and a Cognitive map visualising the complexity of the interplay between geotechnical pathogens and emergent social constructs, represented as an array of barriers to geotechnical best practice in highway project development in the Niger Delta region.

The case study findings are subsequently analytically generalised back to serve as a ‘working hypothesis’, useful in studying the impact of geotechnical pathogens in triggering cost overruns, typical of similar heterogeneous wetland geology and socio-cultural setting. This empirically corroborates and advances the validity of geotechnical explanations, amidst the strong dialectical debate in the literature, which features other rival as well as complementary explanations, in accounting for cost overruns in highway projects. The implications of the case study findings in refuting the chief rival explanation to cost overruns is addressed, and the wider policy implications of the research are discussed. The unanticipated theoretical concepts which emerge from the study, as reflexively analysed and cognitively mapped out with the initial geotechnical themes, are infused as part of the study findings, forming a basis of recommendations for further studies. 4.10.3 Reliability of Data used as Evidence in this Case Study

Specific details on the approach to data management in ensuring reliability of evidence tendered in this case study research, is further provided in the subsequent more practical aspects of the overall research design, in terms of the:

 Data types;

 Methods of data collection;  Structure of interviews;  Sample size of interviews;

 Mode of participant recruitment;  Mode of conduct of interviews;  Analytical techniques