Expert Witness Journal Issue 65 February 2026 - Flipbook - Page 30
(b) Earned value analysis
The EV method compares ‘earned’ hours (derived
from the budget) with actual hours to complete
the work (EVA). The di昀昀erence is then used to
determine any productivity loss and the productivity
(or performance) factor (‘PF’).
(c) Programme analysis
Using the earthworks example:
(d) Work or trade sampling
•
Cost-based methods
Productivity-based methods
1. Project-speci昀椀c studies:
1. Estimated v incurred labour
(a) Measured mile analysis
2. Estimated v used cost
(e) System dynamics modelling
2. Project-comparison studies
3. Industry studies
•
of preference. The cost-based are considered to
be the least robust and are mostly used when lost
productivity cannot be reliably calculated.
•
The cost-based methods generally rely upon
comparing actual costs and estimated costs.
•
Of the productivity-based methods, probably the
measured mile is one that is most talked about.
A reason for this is perhaps that it is very easy to
understand. It requires the analyst to compare
actual production during an undisrupted period
of work to the production rate achieved during a
disrupted period.
The contractor budgeted that it would take 144
machine (CAT637) hours to move 15,000m3 of
material to the stockpile. This is the Earned
Value for this work.
If 72 machine hours have been recorded to date,
then the EV method estimates that 50% of the
work has (or should have been) completed.
If the contractor has actually spent 243 machine
hours to complete the work, then 99 machine
hours measured as lost productivity (144hrs –
243hrs = -99hrs).
The productivity factor is calculated by dividing
the earned hours by the actual hours:
ɿ
144 / 243 = 0.59
This is a 41% loss in productivity.
If the contractor is able to carry out these
calculations early enough in the programme, it has
the opportunity to make informed decisions with
regard to improving the productivity factor, this is
Earned Value Management.
The measured mile is very good, however, as with
most methods, it does have its limitations. A
limitation which is often discussed is that it requires
the analyst to ‘昀椀nd’ a piece of the same or similar
work that has not been disrupted. Having done that
– and this is not as easy as it sounds by the way –
the undisrupted period must be over a reasonable
length of time to con昀椀dently determine a trend.
Another problem might be the identi昀椀cation of
disruption taking place. In my pipework installation
example, the measured mile would show that
production is being achieved therefore there is no
disruption - it does not automatically identify lower
productivity.
A better option, particularly during the ‘live’ works
might be an Earned Value calculation.
What is Earned Value?
Earned value (generally referred to as Earned
Value Analysis ‘EVA’ or Earned Value Management
‘EVM’) is a technique used in project management
to measure performance of a project.
The analysis combines project budget and the
programme to determine the value of work that has
been completed to date. It can be applied across the
entire project, speci昀椀c sections of work or selected
activities.
A simpli昀椀ed EV equation is:
EV = % of work completed x budget
EXPERT WITNESS JOURNAL
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FEBRUARY 2026
