Data Collection

The data collection process is intended to obtain data that will be used to develop and validate the model. The data needed can be divided into three types, namely risk factors that are significant to building and infrastructure works, fuzzy expert system properties such as fuzzy membership function, rule base and fuzzy inference mechanism, and project data. The data were obtained from literature as well as from field survey.

3.3.1 Data Collection from Literature

A review was conducted by collecting published papers and books that relate to cost contingency model behavior. This contingency behavior will be used as the basis for model development. The type of risk factors might vary from one project to another and between each contractor. However, in this research context, only common risk factors that are usually faced by contractors during the construction process will be used in the model.

Risk factors that are considered significant by contractors for building and infrastructure works are identified through the literature review. The risk factor types obtained from the literature survey are then used to develop a conceptual model, which is the basis for the implementation of the fuzzy expert system.

During the literature review, information regarding the fuzzy expert system properties for each variable in the cost contingency model was also reviewed. Among the information is the universe of discourse in the fuzzy set membership function, the fuzzy inference mechanism procedure consisting of components such as fuzzification procedure, fuzzy rule evaluation, implication process, and defuzzification method.

Chapter 3. Research Methodology 40

3.3.1.1 Determination of Risk Factor used in The Model

The step to determine the type of risk factor used in the model is adapted from the method proposed by Wiguna [33]. This method was used since it proposes a technique on how to determine risk factor used in the model by utilizing risk factors from literatures. Several risk factors in construction project can be easily found from literatures [34], [1], [11], [35], [7], [36]. The step can be divided into three parts, namely, identification of all risk factors in the building and infrastructure work, risk factor classification, and risk screening and developing the risk factor relationship.

In the identification step, all risk factors that are related to common construction projects such as building and infrastructure work are identified through the literature review. In the risk classification step, the identified risk factors are then classified according to the characteristic. Similar risk factors that belong to the same classification are combined.

For the risk screening step, the combined risk factors above are further reviewed and reduced to make it easier for the interview respondent during the interview session (Section 3.3.2). Risk factors that are usually not considered by contractors, either because they can be shared or transferred to other parties are removed in order to reduce the number of risk factors.

Finally, the risk factor types that have been reduced are then used to produce the project risk hierarchy. An event tree diagram can be used to compose the project risk hierarchy. Alternatively, an influence diagram can also be used to relate each risk factor and the total project risk. In this research an event tree diagram has been used.

3.3.2 Data Collection from Interview Survey

Survey has been chosen as the method for collecting project data to capture the expert’s knowledge regarding the cost contingency behavior. According to

Chapter 3. Research Methodology 41 Denscombe [37], interview is used as a technique to obtain an insight and in depth information into the topic. In this study, detailed information on cost contingency practices from the construction experts can be obtained through the interview.

The interviews were conducted selectively with eight contractors in the G7 class (large contractors) of Construction Industry Development Board (CIDB) who are located in Selangor, Penang and Perak, Malaysia. In this research, the tender price estimation is assumed as independent of the contractor’s location since in the Malaysian system, all G7 contractors are allowed to operate outside their locations. This means that their practice should be the same anywhere in Malaysia.

The experts who have been chosen as the interviewees are project managers mostly having more than 10 years of working experience in the construction industry. The choice on project managers was made because they usually have a more comprehensive understanding of the project rather than the lower-ranking construction personnel such as estimators or work superintendents.

The projects selected for the surveys are those completed projects, which did not face cost overruns. In other words, the actual cost contingency of the project was just the right amount which is usually between 1 to 10% [38].

Experts in the construction industry have been interviewed to obtain project cost contingency data based on their previous project experiences. The project cost contingency values together with the risk factors that are significant to the project and their risk parameter values are then subjected to the construction expert’s evaluation.

The interview form consists of two sections, respondent information and case project for cost contingency estimation. The first section is mainly intended to obtain information regarding the interviewees’ experiences in construction projects. The second section is intended to obtain information related to the project and the expert’s estimation for cost contingency. Expert judgments in terms of risk likelihood (RL)

Chapter 3. Research Methodology 42 and risk severity (RS) are required for those risk factors that are significant to their project.