The influence of estimator attitude on project cost reliability

The reliability of project estimates is dependent on a number of factors that can be classed as exogenous or endogenous to the estimator. The exogenous factors comprise information, environment, technology, methods and processes, which are external to the estimator. The endogenous factors reflect personal characteristics associated with the estimator and consist of aspects such as judgement, preferences and personality. Construction’s effort to improve the estimating function has addressed both the practice of, and process of delivering the estimate. Much of the effort, however, has been addressed at aspects of estimating that can be considered classed under exogenous factors. This includes the use of technology to improve both the accuracy of computation and the speed for generating the estimate. Notwithstanding progressive improvement achieved in estimating from addressing such exogenous factors, most project-oriented industries still suffer from unreliable estimates. Although the problem of unreliable estimates is a worldwide phenomenon, it reflects more starkly in many developing economies, where its effect is much more striking. Understanding the root causes of the persistence of unreliable estimates would therefore, call for a focus on factors other than the exogenous ones that most improvement and development efforts have focus on. The study, which formed the basis of this thesis adopts the position that any improvements in reliability, beyond what the exogenous-based developments have achieved so far, lies in the contribution that estimators can make by addressing their endogenous factors. For that position to be valid, the study showed that the personality characteristics of various estimators produce different levels of reliability. Three endogenous factors, experience, qualification, and personality archetype (or trait) were employed to explore the relationships with estimating reliability. A quantitative research approach was adopted for the investigation, as the nature of evidence required was primarily objective, to substantiate the argument that different levels of particular endogenous factors produce different reliabilities in estimating. Data for the study was obtained from Ghana. Two categories of sample data were collected through stratification of the population, followed by systematic sampling methods. The two samples were a control group, comprising estimators with more than or equal to ten years experience; and an observed (or study group), made up of estimators with less than ten years experience. An instrument based on a self-reporting protocol was developed and utilized in the elicitation of data from both groups.