A Comparison Of Different Project Duration Forecasting Methods

INTERNATIONAL JOURNAL OF

PROJECT
MANAGEMENT
International Journal of Project Management 24 (2006) 289–302
www.elsevier.com/locate/ijproman

A comparison of different project duration forecasting methods
using earned value metrics
Stephan Vandevoorde

a,1

, Mario Vanhoucke

b,c,*

a
Fabricom Airport Systems, Rue Gatti de Gamond 254, B-1180 Brussels, Belgium
Department ofManagement Information, Operations Management and Technology Policy, Faculty of Economics and
Business Administration, Ghent University, Hoveniersberg 24, B-9000 Gent, Belgium
Operations and Technology Management Centre, Vlerick Leuven Gent Management School, Reep 1, B-9000 Gent, Belgium
b

c

Received 28 June 2005; received in revised form 13 September 2005; accepted 14 October 2005

AbstractEarned value project management is a well-known management system that integrates cost, schedule and technical performance. It
allows the calculation of cost and schedule variances and performance indices and forecasts of project cost and schedule duration. The
earned value method provides early indications of project performance to highlight the need for eventual corrective action.
Earnedvalue management was originally developed for cost management and has not widely been used for forecasting project duration. However, recent research trends show an increase of interest to use performance indicators for predicting total project duration. In
this paper, we give an overview of the state-of-the-art knowledge for this new research trend to bring clarity in the often confusingterminology.
The purpose of this paper is 3-fold. First, we compare the classic earned value performance indicators SV and SPI with the newly
developed earned schedule performance indicators SV(t) and SPI(t). Next, we present a generic schedule forecasting formula applicable
in different project situations and compare the three methods from literature to forecast total project duration. Finally, weillustrate the
use of each method on a simple one activity example project and on real-life project data.
Ó 2005 Elsevier Ltd and IPMA. All rights reserved.
Keywords: Earned value; Earned duration; Earned schedule; Project duration forecasting

1. Schedule performance indicators
Earned Value Management (EVM) is a methodology
used to measure and communicate the real physical progress of a projectand to integrate the three critical elements of project management (scope, time and cost
management). It takes into account the work complete,
the time taken and the costs incurred to complete the

*
Corresponding author. Tel.: +32 9 2643569/2109781; fax: +32 9
2644286/2109803.
E-mail addresses: stephan.vandevoorde@fabricom-gti.com (S. Vandevoorde), mario.vanhoucke@ugent.be,mario.vanhoucke@vlerick.be (M.
Vanhoucke).
1
Tel.: + 32 0 2 3703111; fax: + 32 0 2 3703222.

0263-7863/$30.00 Ó 2005 Elsevier Ltd and IPMA. All rights reserved.
doi:10.1016/j.ijproman.2005.10.004

project and it helps to evaluate and control project risk
by measuring project progress in monetary terms. The
basic principles and the use in practice have been comprehensively described in many sources(for an overview,
see, e.g. [1] or [2]).
Although EVM has been setup to follow-up both time
and cost, the majority of the research has been focused
on the cost aspect (see, e.g. the paper written by Fleming
and Koppelman [3] who discuss earned value management
from a price-tag point-of-view). Nevertheless, earned value
management provides two well-known schedule performance indices, theschedule variance (SV) and the schedule
performance index (SPI), to measure project progress. The
SV is the difference between the earned value (EV) and the
planned value (PV), i.e. SV = EV À PV (for a graphical

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S. Vandevoorde, M. Vanhoucke / International Journal of Project Management 24 (2006) 289–302

In order to overcome the anomalies with the earned
value schedule performance...