DEMITONResearch / Rework statistics / Mean design error cost 14.2% of contract value, 139 Australian projects
Mean design error cost 14.2% of contract value, 139 Australian projects
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14.2% of contract value: Mean design error cost 14.2% of contract value, 139 Australian projects (Love, Lopez, Kim & Kim, 2014, and 1 other source; Australia; moderate confidence).
What it is. 14.2% of original contract value, cost of design errors, direct and indirect, as estimated by survey respondents.
Sample. Questionnaire survey of 139 Australian projects. The 2012 paper gives a mean direct design error cost of 6.85% and a mean indirect cost of 7.36% of contract value; the 2014 paper gives a mean design error cost of 14.2%. 6.85 plus 7.36 is 14.21, so the two appear to describe the same sample, which the abstracts do not state outright.
What it is not. Respondents' estimates of design error cost, not measured cost records, and the abstracts do not say who carried the cost (contractor, designer or client), so it is filed as money at stake and not as contractor loss. Abstracts only: the full texts were not read. The 2012 abstract says cost did not vary significantly by project type, while the 2014 abstract reports significant differences by type, which the abstracts do not reconcile. The 2012 abstract does not name the country, so that source is filed as unknown; Australia rests on the two 2014 abstracts, which both say 139 Australian projects, and neither names the states or says how the projects were drawn, so how national the sample is cannot be told from them. It is larger than the 12.3% total rework cost the same group reports for 161 projects, so it is a cost of design errors and their effects, not a share of rework. That the 2012 and 2014 papers share one sample rests on the matching 139 and the sum 14.21, not on a statement.
Where it came from
- Love, Lopez, Kim & Kim (2014), Probabilistic assessment of design error costsabstract, as held in the Curtin University repository record (read through its mirror at cendekia.unisza.edu.my/neuaxis-e/Record/curtin-20.500.11937-10591/Details); the ASCE page was not opened and the full text was not read · source record
- Lopez & Love (2012), Design Error Costs in Construction Projectsabstract, as held in the Curtin University repository record (read through its mirror at cendekia.unisza.edu.my/neuaxis-e/Record/curtin-20.500.11937-10508/Details); the ASCE page returned 403 and the full text was not read · source record
Considered and set aside
- Love, Lopez, Kim & Kim: Reports the same 14.2% for the same 139 Australian projects in a second paper by the same group, so it is the same sample read again, not independent corroboration.
- Love, Edwards & Smith: A survey of 161 Australian projects that found no significant relationship between contract documentation and rework cost. It gives no share of contract value for documentation, so it does not give a figure for this cause.
- Australian Constructors Association and Consult Australia: Says late design changes and unclear scope drive cost into major projects, with no figure, sample or data source.