文献信息：

文献标题：Factors influencing accuracy of construction project cost estimates in Pakistan: Perception and reality（影响巴基斯坦建设工程造价估算准确性的感知因素和实际因素）

国外作者：Farrukh Arif，Sarosh H. Lodi，Nida Azhar

文献出处：《International Journal of Construction Management》, 2015,15(1):59-70

字数统计：英文3023单词，17564字符；中文5181汉字

外文文献：

Factors influencing accuracy of construction project cost

estimates in Pakistan: Perception and reality

AbstractConstruction projects are unique as they are priced before being constructed. Therefore, accuracy of construction project cost estimates is pivotal in project success. Several studies have determined factors influencing the accuracy of cost estimates. Comparatively less information is available for construction industries in developing countries. This study identified factors influencing the accuracy of cost estimates for construction projects in Pakistan. Cost data was collected for 46 completed construction projects. Four dimensions 60 factors were considered. Dimensions included: project characteristics, project team, estimating procedures, and (costing related) information items. A rigorous analysis framework based on principal component analysis and regression analysis was used. Involvement of the contractor in the estimation procedure and labour rates were found to be the most significant factors. Early involvement of the contractor can result in realistic estimates through timely input from subcontractors, materials suppliers and manufacturers among others. This also helps in controlling labour costs as most of the construction projects in Pakistan employ labour through subcontractors.

Keywords: cost estimates; Pakistan; factors influencing accuracy; estimate bias; estimate consistency; principal component analysis; regression analysis

Introduction

The construction industry is unique in its working as compared to other manufacturing and product development industries. Since it is a project-based activity, every construction project has its own nature, requirements, and characteristics. The uniqueness of construction projects is that they are priced before being constructed. Therefore, accuracy of project estimates have a pivotal role. This is the reason that more often than not, comparison of actual cost to early cost estimates becomes the measure of the project team, performance and overall success of the project (Oberlender & Trost 2001). Pricing and the profit required from the construction project are decided at the time of bidding and the bid’s acceptance (Halpin & Senior 2009). Therefore, construction project managers are primarily involved in cost control. This makes it necessary for construction managers to understand different factors that influence the accuracy of project cost estimates. Several researchers have conducted detailed studies in order to determine factors influencing the accuracy of cost estimates. However, comparatively less information on this is available for the construction industries in developing countries. Realizing this need, the paper presents a rigorous analysis to determine factors influencing the accuracy of construction cost estimates. The data was collected from 46 construction projects in Pakistan. The authors adopted a two-stage statistical analysis framework to determine the perceived and real factors influencing the accuracy of estimates of construction project costs. Certain conclusions have been drawn and strategic-level recommendations are provided, based on results of the analysis, to improve the cost estimation process and to reduce inaccuracy in the construction industry of Pakistan.

The study presented in this paper first provides a brief synopsis of similar prior studies conducted from different perspectives. Then it provides an account of the research objectives and scope, followed by details on research methodology and data collection. The main part of the paper provides details of the data analysis and its

results. This is followed by discussion of results of the analysis. Finally, strategic-level recommendations are provided for the improvement of cost estimation practices in the construction industry of Pakistan which could be equally applicable for other developing construction industries.

Prior studies

Several studies have been conducted related to accuracy of cost estimates for construction projects. On many occasions, researchers have attempted to measure the impact of certain project characteristics on the accuracy ofestimates (Skitmore 1988; Akintoye &Fitzgerald2000). Akintoye (2000) conducted a study to identify and understand the factors that influence contractors’ cost estimation practices in the UK. It was concluded that the main factors influencing cost estimating practices included the complexity of the project, the scale andscopeoftheconstruction, market conditions, the method of construction, site constraints and location. Aibinu and Pasco (2008) conducted a study to explore the accuracy of pre-tender building cost estimates in Australia. They identified eightproject characteristics and conducted analysis using multiple regression analysis; they found that the accuracy ofestimates is influenced by project size.

On the other hand, certain other studies had not only accounted for project characteristics but also other aspects,such as project team-related factors, estimating procedures, and (costing related) information items. Carr (1989) conducted a study to define the basic requirements for developing reliable estimates. He concluded that the accuracy of the estimate depends on the estimator’s ability to see the project from a macro perspective, his experience and judgement skills. Ashwarth (1994) concluded that availability of information on the design, type and quality of cost data, type of project, project size, number of bidders on competitive projects, stability of market conditions, personal factors, proficiency in estimating, and sheer quantitative experience influence the accuracy of estimating the costs of construction work. Oberlender and Trost (2001) developed an estimate scoring system and consequently software to measure the accuracy of estimates. They found that the accuracyof an