CONTENTS

DURATION ESTIMATION OF A WORK PACKAGE 217
the relation (2) needs a correction, which will adjust D with a coefficient resulted
from the P id of each project team member. The P id can be calculated as a report
between the estimated (Ecest) and the actual effort (Ecreal) a team member spent on
the c component:
(3) P idi = ECreal
ECest
Depending on how the original estimations were performed, based on the organization
historical data using T P E technique, or based on a single person experience, the P id
will reflect the person’s relative productivity compared to the organization’s average
or compared to that person productivity. If we introduce relation (3) in relation (2),
the result will be an adjusted D (Dadj):
(4) Dadj = EW P
=
P idi
EW P
P ·
−1 P idi
=
P
EW P
P · prod
i
where prod is the team’s productivity coefficient. The value of prod can be influenced
by the correctness of the E estimations and the learning curve of the personal. For
more accurate prod calculations, the P idi needs to be calculated based on historical
data, or predicted, taking into the trend of its professional evolution. In some situations,
like new team members, new project type where no historical data can be
used, the estimation will be erroneous. For this situation Dadj should be adjusted
periodically during the project, by predicting the prod of the team based on their
evaluation till that moment in the project.
Figure 1. Comparing D estimations
Figure 1 shows the different results of the estimations: D1 was estimated with
relation (2), D2 with the adjusted relation (4) and since the real progress is slower
then expected, after the prod readjustments the D4 is obtained, which is more realistic
then the previous ones.
4. Conclusion
Estimation of WP duration is a difficult and key problem in software engineering.
There are several estimation models, but most of them are adjusted for medium and
i