Prequalification Model for Responding to Contractors’ Selection Problems in Construction Projects

contractors have different levels of cost, quality, efficiency, and technical know-how. The selection of a qualified contractor gives confidence to the employer that the selected contractor can achieve the project goals.

Babalola affirmed that appraising the diverse pressure limits associated with construction project success requires that selection of contractors is highly important. Ng and Skitmore were of the view that contractor selection is a decision characterized by multiple and conflicting objectives since the client wants to minimize the likely cost of the construction project, but also wants contractors to maintain schedules as well as achieving acceptable quality standards. However, contractors may be selected on the basis of competition or negotiation.

The competitive process is conventionally regarded as the most efficient means of producing the proper and fit contractor al resonated with the view that competitive bidding is still the most acceptable method of evaluating contractor’s suitability since they are faced with highly competitive pressure. On the other hand, negotiation makes it possible to use a contractor’s knowledge of construction method and cost to advantage and by mutual agreement to specify contract duration and/or conditions of payment to produce the most effective and advantageous bargain.

The tendering process according to Jagboro is aimed at selecting a suitable contractor and obtaining from there an appropriate time an offer or tender which is capable of forming the basis for a workable agreement. Aje (2008) agreed with the above, that the tendering stage is the focal point of all the construction stages which depicts the stage at which a construction project is handed over to a contractor for execution on the basis of his competence. In summary, the selection of a construction

contractor requires a careful assessment which is done on the basis of their prequalification evaluation.

Definition of Term

Prequalification is a pre-tender process used to investigate and assess the capabilities of contractors to carry out a contract satisfactory should it be awarded to them. In other words, pre-qualification is a prerequisite for the selection of contractors.

The prequalification process according to different pieces of literature including but not limited to Hunt et. al., 1996; Merna and Smith, 1990; Holt et. al; 1994, Potter and Savindo; 1994 Hatush and Skitmore 1997

Materials and method

Apparatus In this study, two sets of instruments were used to collect data in the form of questionnaires. The parameters that generated the data include different contractor’s prequalification criteria, initial contract sum, initial contract period, final contract period, and the final cost of construction. The collection of secondary data with the other part of the questionnaire was aimed at consultants providing some case study data on completed projects. Sampling Frame The selection of respondents for this study was by random sampling technique.

The population of the study was marked out by the roles and responsibilities of all construction work stakeholders in the contractor’s selection. The Niger Delta region of Nigeria was purposefully selected because of the numerous construction work going on in the region after the amnesty declaration for militants as one of the rehabilitation strategies. The questionnaire was administered to consulting Architectural, Quantity Surveying, Electrical, and Mechanical Engineering, Civil Engineering firms, contracting firms, government ministries, and parastatals in the Niger Delta region. Analytical Technique Employed

The main aim of this study is to assess the factors of contractor’s pre-qualification criteria for eventual selection towards construction project

delivery in the Niger-Delta region of Nigeria vides modeling. A prequalification criterion has effect on completion cost, value and duration of construction projects. Data collected through questionnaire was collected and analysed to evaluate how contractor’s prequalification selection affects cost, duration, and quality of construction projects in the region by the use of:

• Measures of central tendency with ranking
• Pearson correlation matrix
• Analysis of variance

Results and Discussion

Data Presentation and Analysis This section presents an in-depth appraisal and analysis of the results obtained from the field survey experimentation. In the presentation, various simplified tables and figures were generated from the questionnaire coded form. The field survey captured fifty-six projects where contractors were selected from their prequalification evaluations with $1 to N158, the total value of projects executed for evaluation is presented below;

A model for prediction will now be made to evaluate the contractor’s selection based on the attainment of the various prequalification criteria. Model Specification A simple regression and correlation matrix model was formulated for this study. The model is specified below:? t + t. Where are parameters to be estimated and? t = error term that is identically and independently distributed with mean zero and variance zero. Prequalification Model The model is given as follows? t + 0. 585 Testing hypothesis about the coefficients at 5% significance level.

1. Constant H0:

Constant = 0 H1: Constant ?

Outcome: Since the significant value of 0. 111 is greater than 0. 05 we conclude that the constant is not significantly different from zero. H0: = 0 H1:?

Outcome: Since the significant value of 0. 611 is greater than 0. 05 we conclude that is not significantly different from 0. 3. H0: = 0

H1: ?

Outcome: Since the probability value of 0. 760 is greater than 0. 05 we conclude that is not significantly different from 0. 4. H0: = 0 H1: ?

Outcome: Since the probability value of 0. l034 is less than 0. 05, we conclude that is significantly different from 0.

Summary

Conclusion and Recommendation In this study 83 questionnaires were distributed with 56 responses.

Because of the very nature of distribution systems the vector field of the population will tend behave to some know statistical distribution formulation and evaluated as such. Findings showed that, the basis of contractor’s selection is dependent on the evaluation of their:

1. Prequalification score
2. Final cost of completion
3. Eventual completion time
4. Quality control score These parameters were evaluated on the basis of the contractor’s technical capability, financial strength, quality assurance policy, contractor’s reputation and image, managerial capability, health, and safety policy, and the general outlook of the company.

The study came up with a linear mathematical model for the evaluation of contractor’s prequalification score in percentage for his eventual selection which 25% of the population constituting 14 respondents of 56 samples agreed that cut-off mark for contractor’s selection should be 61 – 70% value of the model on the preponderance of the contractor’s presentations on the above variables. Further, contractors tend to downplay their quality, health, and safety policies at the expense of profit maximization.

Acknowledgement

The authors are highly indebted to students of Quantity Surveying and Civil Engineering departments for their assistance in locating, distributing and retrieving of questionnaires that were used as data collection instruments for the study. Also, various professionals in the field of consultancy, contracting, and government departments are also acknowledged for responding to

the questionnaires.

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