Time and cost models for building projects using prequalification and contract award data in Nigeria
The purpose of this study was to develop models for predicting the probable completion cost and time of building projectsusing contractors' prequalification assessment, the initial contract sum and the proposed contract duration.Data on Contractors' Prequalification Assessment (CPA), Initial Contract Sum (ICS), Planned Contract Duration (PCD), Project Completion Cost (PCC) and Actual Contract Duration (ACD) for 77 completed building projects were sourced from Bureau of Public Procurement (BPP). Multi-colinearity test was conducted on the variables in order to avoid multiple correlations among the data before subjecting them to Multiple Regression Analysis (MRA). The goodness of fit of the models derived as defined by the value of R2 was found to be 98.2% and 92.80% for cost and time; thus signifying thatabout 2% and 7% of the residual variations in the independent variables were not included in the cost and time models respectively. The result of the research would therefore be a bold step at selecting competent contractors who can deliver projects to time and within budgeted cost in Nigeria.