Construction procurement system is the organizational framework adopted by the client for the management of design and construction of a project. With the introduction of new and innovative ways of construction, many new and alternative procurement systems have been developed over the past decades. These systems could be used to meet contemporary requirements of the clients. Different procurement systems are used for different projects and the correct choice may help to avoid problems and be the key to the attainment of project specific goals.
From the clients’ point of view, there are probably only three basic criteria which include cost, time and quality. Hence, traditional procurement selection processes result in clients prioritizing the basic criteria of Time, Cost, and Quality.

The lack of structured procedures, based on good information, for the selection of construction procurement system sometimes inhabit the opportunity for client to choose a procurement option in a fully informed manner.

Each project in the industry has its own characteristics and the project to be success the procurement method must address the technical features of the project alongside the client’s and contractor’s needs. The selection of suitable procurement method is critical to the success of any project.

Procurement selection

Several previous studies have identified number of factors influencing the selection of procurement system in construction. They have focused on selection factors in terms of Client characteristics, Project requirements and External environment.

From the synthesis of the outcome of past studies, overall factors affecting the procurement selection can be grouped under three main criteria. The Figure portrays the conceptual framework developed based on the project’s environments which determine the selection criteria
DELPHI TECHNIQUE IN PROCUREMENT SYSTEMS OF CONSTRUCTION PROJECTS
There have been several models developed with the intention of facilitating the selection of suitable procurement system for a particular project. Among the various models, Multi Attribute Utility Technique (MAUT) received the greatest attention.

One of strongest criticisms was the selection of procurement variables. The other is the utility value developed through opinions of industry experts.

Methodology
The use of Multi Attribute Decision Analysis has been considered the foremost technique for examining client needs and weighting of preferences from experts for each procurement, but the major difficulty with these selection systems lies in the lack of consensus among the experts on the utility factors.

To overcome above deficiencies, the Delphi technique was adopted. Delphi method is a highly formalized method of communication that is designed to extract the maximum amount of unbiased information from a panel of experts.

The success of the Delphi method principally depends on the careful selection of the panel of experts. In order to meet all stipulated requirements and to increase efficiency of the outcomes, the sample size was selected to have upper limit of the reliable sample size (15- 35) of the Delphi technique.

Thirty five (35) members of panel represent wide distribution of professionals from several disciplines including Project Management, Quantity Surveying, and Engineering from consultant & contractor organizations both in public and private sectors.

The Purposive selective sampling has been used as the appropriate sampling method for this research, because the information obtained from experts required in depth knowledge and sound experience on various procurement options. A group of experts, who have relevant working experience in the field of construction management and procurement selection, were selected to get the opinion on selection criteria and their level of influence on various procurement systems in construction.

The following Table gives the profile of the experts involved in the survey
DELPHI TECHNIQUE IN PROCUREMENT SYSTEMS OF CONSTRUCTION PROJECTS
The Table 2 presents the formats of Delphi survey carried out in four rounds and briefly introduces the data evaluation techniques used to analyze the data collected from the survey
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Findings
· Review of literature in Delphi round one.
· In the second round level of importance of each factor was considered.
· Third round targeted to derive the utility values
· fourth round comprised with the average utility values

The questionnaire used in fourth round comprised with the average utility values derived from 25 experts for each factors against various procurement systems. The respondents were asked to reconsider the results of round three in order to improve the consistency of the results. There were 23 out of 25 questionnaires received in the fourth round and they were considered for the analysis at the end of fourth round.

Client’s requirements

Utility values of all nine factors were sufficiently consistent at 0.05 level of significance or smaller. Further, concordance coefficient (w) ranges between 0.08 – 0.46 for certain factors indicating less strong agreement among experts during round three. The concordance coefficient ranges between 0.59 – 0.74 indicate the strong agreement among experts at the fourth round of Delphi. The concordance analysis shows that the consistency of the experts’ ranking for procurement systems against each factor has improved over the succeeding round.
Therefore, it can be concluded that all nine factors significantly influence the procurement selection practices.

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Project Characteristics
Utility values of all six factors were sufficiently consistent at 0.05 level of significance or smaller. Further, concordance coefficient (w) ranges between 0.29 – 0.38 for all six factors indicate less strong agreement among experts during Delphi round three. The concordance analysis shows that the consistency of the experts’ ranking for procurement systems against each factor has improved over the successive round.
The coefficient of concordance for all six factors improved from 154.64% to 581.644%. In this round, six factors were considered sufficiently consistent compared to previous round. The results shows that the experts had overcome the difficulty in assessing the factor such as Project type, since the significance improved lesser than 0.05 (? reduced from 0.2613 to 0.0000 in the successive rounds).

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External Environment
With respect to the external environment, utility values of all five factors were sufficiently consistent at 0.05 level of significance or smaller.  On the other hand, the correlation between the experts regarding the external environmental factors has also been increased. These external environmental factors have either direct or indirect influence on the selection and use of the procurement systems. Therefore, in assessing the suitability of a procurement system, the underplaying relationships of external environment need to be considered to avoid the consequences in decision making.

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Conclusion
An exclusive set of multiple decisive factors in terms of main three criteria: Clients’ requirements & objectives, Project characteristics and External Environment, have been identified as being generally adequate for the procurement selection and there is a reasonable consensus on utility values for each procurement system.
This study has used Delphi technique to ensure that the consensus is reached for the utility values provided by the panel of experts/practitioners from the industry. The synthesis of the outcome of the survey demonstrates intensely that there is a significant improvement in the consistency of the utility values over the successive Delphi rounds.

From this study it was found that all identified factors in terms of clients’ requirements and project characteristics have greater level of influence on procurement selection. The importance and interrelationships of identified significant factors and the utility values provide a good background for the development of procurement selection criteria for any kind of project scenario. The selection criteria should be logically derived from project’s internal and external environment.