While most writings imply that construction cost estimating is a combination of art and science, below are the reasons why Construction Cost Estimating is NOT and ART.
Construction Cost Estimating is NOT and ART and though the debate of art vs. science with continue, my vote is “highly technical profession”.
#1 Construction cost estimating is a profession. Construction cost estimating takes decades of multi-discipline experience. An understanding of diverse construction means and methods is required, and the potential impacts of multiple sources of variation must be considered. The application of this knowledge is not so much an art, but a true professional learned discipline. Just like a surgeon, practice, practice, and more practice, leveraging proven methods and techniques is the path to consistently positive outcomes.
#2 Robust Process is critical. The application of a consistent robust process is mandatory elements to ensuring consistent, verifiable, defensible, and detailed construction cost estimates. A detailed line item estimate inclusive of quantities and granular task descriptions inclusive of local market labor, material, equipment, and productivity data and costs is the only pathway to best possible estimation. (Process: A sequence or flow of Activities in an organization with the objective of carrying out work.)
#3 Knowledge of Teams and People. Productivity is clearly linked to the people involved at all levels of a repair, renovation, maintenance, or new build activity. A construction cost estimator can only create information with the assumption that the people involved have the appropriate levels of capacity and capability.
#4 There is no such thing as an accurate construction cost estimate. A construction can be defensible, verifiable, and detailed, but never accurate. Measuring accuracy required the ability to be validated/measure against a control. There simply is no “control”. Using actual construction costs clearly is inappropriate. Using similar recently completely project also includes far too many variables.
While the debate of art vs. science or both, will continue. My vote is a that it’s a profession and highly technical/experience based. If one wishes to call “expert judgement” an art, then that’s one thing. Expert judgement is certainly required to validate process and outputs. As noted, I consider expert judgement a learned attribute.
We always need the expert judgement – the issue is sometimes to get hold of the experts at the right time. There are many benefits for the quality of the estimates if it is validated by an estimating expert – even if it is late in the life cycle.
Estimating as a process – The Estimating process is the combination of different techniques and solutions to drive a high quality result. (Green, C. 2006)
“Definition of estimating – A quantitative assessment of the likely amount or outcome. Usually applied to project costs, resources, effort and duration and is usually preceded by a modifier (i.e., preliminary, conceptual, feasibility, order-of-magnitude, definitive). It should always include some indication of accuracy (e.g. ±x percent).(A Guide to the Project Management Body of Knowledge (PMBOK® Guide, p. 380)”
via 4bt.us
Green, C. (2006)