Installation labor and productivity estimating · Lesson 4 of 4

Installation labor and productivity estimating: defects, verification and case study

How to compare planned with actual hours using the Delta, a published sheet-metal case study, four common estimating defects, how to verify an estimate while the work runs, and why lost hours are never recovered by dropping protection.

You will be able to: Diagnose a plausible installation estimating defect, check planned hours against actual, and document the evidence for review.

13 min · 10 slides · 13 questions

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Slide 1 of 10

Planned versus actual: the Delta

Hanna defines Delta as actual labor hours minus the estimated hours including approved change orders. A positive Delta means actual productivity was worse than estimated.

%Delta is Delta divided by the actual hours.

Causes the study names include an inaccurate estimate, contractor inefficiency, change orders, weather and interruptions.

Sources

Schedule Compression Effects on Labor Productivity (A.S. Hanna, University of Wisconsin-Madison, 2004; Appendix II multipliers) - New Horizons Foundation (SMACNA resource library)

Glossary

Delta: Actual labor hours minus the estimated hours including approved change-order hours. A positive Delta means actual productivity was worse than estimated (Hanna).
Percent Delta: Delta divided by the actual hours, as Hanna defines it.
Work sampling: Recording what a worker is doing at fixed intervals, such as every 60 seconds, to learn the share of time spent on direct work.
Applicability range: The span of inputs a published equation or table was built on, such as 5 to 50 percent overtime. Outside it the figure is not applied.