Earned Value Analysis Exercise: Author: Revision
Earned Value Analysis Exercise: Author: Revision
Earned Value Analysis Exercise: Author: Revision
www.spmbook.com
Author: Adolfo Villafiorita
Revision: 2 (2015-02-06)
Perform an analysis of the project status at week 13, using EVA. Use the CPI and SPI to determine
project efficiency.
Solution
Earned Value Analysis is discussed in: http://www.spmbook.com/downloads/slides/pdf/C03-08-09-
ExecutionMonitoringControl.key.pdf
We organize the solution as follows:
1. Drawing the Gantt chart of the plan
2. Drawing the Gantt chart of the actual plan (progress status)
3. Perform the analysis (plot PV, AC, EV, CPI, SPI)
The Gantt chart can now be easily drawn, by taking into account the expected duration of each
activity. The result is shown in the following diagram (notice that we are assuming the duration to
be expressed in working-days and that we are using a standard calendar, in which saturday and
sunday are non-working time):
2. Drawing the Gantt chart of the actual plan (progress status)
The actual Gantt chart can be drawn by taking into account the information about delays, variations
in duration, and actual completion. The main point of attention (when doing this work manually), is
taking into account the constraints. Gantt charting tools, fortunately, can do this for us
automatically.
The following figure shows the two plans, the baseline (or initial) plan, shown in the lower part of
each activity and the actual plan, shown in the upper part of each activity:
As it can ben seen, the delay on activity B delays all other activities in the plan. The activities
marked in red are in the critical path.
PV is the sum of planned costs. It is computed by determining for each reporting period, the cost
associated to each activity and by summing and cumulating them over time.
The following table summarizes the planned costs over time. It is computed as follows:
Each column of the table represents one week (we show only the first 13 weeks)
The planned costs of each activity is taken from the first table of the question
For each activity, we compute the weekly cost (activity cost / duration in weeks) and accrue
the cost for each week in which the activity lasts. For instance B has a total planned cost of
10000 and a duration of four weeks, from W2 to W5. Therefore we accrue 2500 in weeks
W2 to W5 for B.
We then compute the cumulative costs, by summing planned expenditure week by week.
EV is the sum of the planned costs on the actual schedule. There are different rules for
computing EV. We use 50%-50% (50% of planned costs when an activity starts, the remaining 50%,
when the activity ends.
The result is shown in the following table:
W1 W2 W3 W4 W5 W6 W7 W8 W9 W10 W11 W12 W13 Total
A Meet with client 500 500
B Write SW 5000 0 0 0 0 5000 10000
C Debug SW 750 750 1500
D Prepare draft manual 1000 1000
E Meet with clients 1000 1000
F Test SW 1000 0 0 1000
G Make modifications 0
H Finalize manual 0
I Advertise 4000 0 4000
Total 500 0 5000 0 0 0 0 5000 1750 1750 1000 4000 0
Earned Value 500 500 5500 5500 5500 5500 5500 10500 12250 14000 15000 19000 19000
We can now plot all three values together. The result is shown in the following diagram:
35000
Planned Value
32000
Actual Costs
Earned Value
30000 28000
24000
25000
21500
19000 19000 19000
20000
16500 16000 16750
15000 15250
15000
14000 14000
15000 13000 12750
12250
10500 10500
9000
10000 8000 7500
5500 5500 6000
5500 5500 5500
4500
5000 3000 3000
1500 1500
500 500
0
W1 W2 W3 W4 W5 W6 W7 W8 W9 W10 W11 W12 W13
From the data at W13 we can observe the following:
PV > AC indicates that the project is under budget. However, it might be under budget
because of two reasons: it is, in fact, efficient or, alas, it is late (the expenditure has not yet
occurred, because activities did not start).
EV < PV indicates that the project is late. At W13, in fact, the value we currently produced
is the one we should have had at W9.
For more precise analyses about the project efficiency, we can compute CPI and SPI, which
measure cost efficiency and schedule efficiency.
More in details: CPI = EV/AC, that is, how many dollars we produce (EV) for each dollar we
spend (AC). Clearly CPI > 1 is a good sign, while CPI < 1 indicates that the project is inefficient
and will probably end over budget.
The following graphs shows the behaviour of CPI over time. If we do not consider some noise (due
to the 50%-50% rule, which causes, for instance, the peak at W3), we can see that CPI is getting
close to 1, indicating that the project should end on budget, if the trend is confirmed.
2 CPI 1.83
1.8
1.6
1.4 1.22 1.19 1.13
1.2
1 0.96 0.93 0.98
1 0.92
0.73
0.8
0.61
0.6
0.33 0.33
0.4
0.2
0
W1 W2 W3 W4 W5 W6 W7 W8 W9 W10 W11 W12 W13
The SPI index measure the schedule: SPI = EV/PV and indicates how much we produce (EV) with
respect to what we thought we would produce. Also in this case SPI > 1 is a good sign (ahead of
schedule), while SPI < 1 indicates that the project is late. In our example we should expect SPI to be
< 1, as it is, in fact, shown by the following diagram, which plots SPI over time:
1.2
SPI
1 1
1
0.8
0.69 0.68
0.64 0.64 0.65 0.63
0.59
0.6 0.52
0.42 0.39
0.4
0.17
0.2
0
W1 W2 W3 W4 W5 W6 W7 W8 W9 W10 W11 W12 W13