Percentage Completion

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Pourcentage d'achèvement : une métrique imparfaite mais courante pour l'avancement des projets

Dans le monde de la gestion de projet, il est tentant de s'appuyer sur le pourcentage d'achèvement comme un moyen rapide et facile de suivre l'avancement. Après tout, cela semble simple : quel pourcentage du travail est effectué ? Cependant, cette métrique trompeusement simple est souvent insuffisante, conduisant à des évaluations inexactes et à des retards potentiels de projet.

Qu'est-ce que le pourcentage d'achèvement ?

Le pourcentage d'achèvement mesure l'avancement d'une tâche ou d'un projet en proportion de sa durée totale. Il est souvent exprimé en pourcentage, 100 % représentant l'achèvement. Par exemple, si une tâche est prévue pour durer 10 jours et que 5 jours se sont écoulés, le pourcentage d'achèvement est de 50 %.

Le défaut de la subjectivité

Le principal problème du pourcentage d'achèvement réside dans sa subjectivité inhérente. Il n'existe aucun moyen objectif unique de déterminer la progression réalisée. Différentes personnes peuvent avoir des interprétations radicalement différentes de ce qui constitue 50 % d'achèvement. Cela peut conduire à des divergences entre les chefs de projet, les membres de l'équipe et les parties prenantes, créant de la confusion et entrave le suivi précis de l'avancement.

Au-delà des limites du pourcentage d'achèvement

Bien que facile à comprendre, le pourcentage d'achèvement manque de la sophistication nécessaire pour refléter fidèlement la progression réelle d'un projet. Il ne tient pas compte de :

Complexité des tâches : une tâche apparemment simple peut prendre plus de temps qu'une tâche plus complexe, même si elles ont la même durée. Le pourcentage d'achèvement ne fait pas la distinction entre ces scénarios.
Disponibilité des ressources : les retards dus à des contraintes de ressources ne sont pas reflétés dans les calculs simples de pourcentage.
Qualité du travail : le pourcentage d'achèvement ne tient pas compte de la qualité du travail effectué. Une tâche peut être techniquement achevée, mais nécessiter une reprise, ce qui entraîne des retards et des ressources gaspillées.

Une meilleure alternative : l'analyse de la valeur acquise

Pour une évaluation plus robuste et précise de l'avancement du projet, l'analyse de la valeur acquise (AVA) est recommandée. L'AVA mesure le travail effectué par rapport au travail planifié, en tenant compte à la fois du calendrier et du budget. Elle utilise des indicateurs clés tels que :

Valeur planifiée (PV) : le coût budgété du travail prévu à être achevé à un moment donné.
Valeur acquise (EV) : la valeur réelle du travail effectué.
Coût réel (AC) : le coût réel engagé pour réaliser le travail.

En comparant ces indicateurs, l'AVA fournit des informations précieuses sur la performance du projet, mettant en évidence les risques potentiels et les opportunités d'amélioration.

Conclusion

Le pourcentage d'achèvement peut sembler convivial, mais sa subjectivité inhérente le rend peu fiable pour une évaluation précise de l'avancement du projet. En adoptant des méthodes plus sophistiquées comme l'analyse de la valeur acquise, les chefs de projet peuvent obtenir une compréhension plus claire de l'avancement réel, gérer les risques efficacement et garantir le succès du projet.

Test Your Knowledge

Quiz: Percentage Completion: A Flawed Metric

Instructions: Choose the best answer for each question.

1. What is the primary problem with using percentage completion as a project progress metric? a) It is too difficult to calculate. b) It does not consider task dependencies. c) It is subjective and can be interpreted differently by individuals. d) It does not account for changes in project scope.

Answer

c) It is subjective and can be interpreted differently by individuals.

2. Which of the following factors does percentage completion NOT account for? a) Task complexity b) Resource availability c) Work quality d) Project budget

Answer

d) Project budget

3. What is a better alternative to percentage completion for assessing project progress? a) Gantt charts b) Earned Value Analysis (EVA) c) Critical Path Method (CPM) d) Agile methodologies

Answer

b) Earned Value Analysis (EVA)

4. What does "Earned Value" represent in Earned Value Analysis? a) The budgeted cost of work scheduled to be completed. b) The actual cost incurred to complete the work. c) The actual value of work completed. d) The difference between the planned value and actual cost.

Answer

c) The actual value of work completed.

5. What is a potential drawback of using percentage completion to track project progress? a) It can lead to inaccurate progress assessments. b) It can create confusion among team members and stakeholders. c) It can hinder effective risk management. d) All of the above.

Answer

d) All of the above.

Exercise: Evaluating Project Progress

Scenario: You are managing a web development project with the following tasks:

Task 1: Design website layout (Estimated time: 5 days)
Task 2: Develop front-end code (Estimated time: 10 days)
Task 3: Develop back-end code (Estimated time: 8 days)
Task 4: Implement database (Estimated time: 3 days)
Task 5: Testing and deployment (Estimated time: 4 days)

Current Progress:

Task 1 is 100% complete.
Task 2 is 50% complete.
Task 3 is 25% complete.
Task 4 has not started.
Task 5 has not started.

Instructions:

Calculate the project completion percentage using the simple percentage completion method.
Explain why this calculation is flawed and what information it does not consider.
Suggest an alternative approach to assessing project progress, using the concept of Earned Value Analysis.

Exercice Correction

1. **Simple Percentage Completion:** Total estimated time: 5 + 10 + 8 + 3 + 4 = 30 days Completed time: 5 (Task 1) + 5 (half of Task 2) = 10 days Percentage completion: (10 / 30) * 100 = **33.33%** 2. **Flawed Calculation:** This calculation is flawed because it only considers the time spent on tasks, not the actual work completed. It doesn't account for the fact that Task 2, which is 50% complete, may be more complex than Task 3, which is only 25% complete. Additionally, it doesn't consider the fact that Task 4 and Task 5 haven't started, even though they are scheduled to take a significant amount of time. 3. **Earned Value Analysis (EVA):** To use EVA, we need to define the following: * **Planned Value (PV):** The budgeted cost of work scheduled to be completed by a specific point in time. * **Earned Value (EV):** The actual value of work completed. * **Actual Cost (AC):** The actual cost incurred to complete the work. For example, let's assume a simple scenario where each task has a fixed budget: * **Task 1:** PV = 100, EV = 100, AC = 100 (assuming it was completed on budget) * **Task 2:** PV = 200, EV = 100, AC = 150 (assuming half the work is done but the cost is higher than planned) * **Task 3:** PV = 160, EV = 40, AC = 50 (assuming only 25% is done and the cost is higher than planned) * **Task 4:** PV = 60, EV = 0, AC = 0 (not started) * **Task 5:** PV = 80, EV = 0, AC = 0 (not started) By calculating PV, EV, and AC for each task, we can get a better understanding of the project's progress and potential risks. For example, we see that Task 2 and Task 3 are over budget, which might require adjustments to the project plan.

Books

Project Management Institute (PMI). (2021). A Guide to the Project Management Body of Knowledge (PMBOK® Guide) – Seventh Edition. PMI Publishing.
- This foundational text for project management covers percentage completion as part of its discussion on project scheduling and progress tracking. It also outlines alternatives like Earned Value Analysis.
Kerzner, H. (2020). Project Management: A Systems Approach to Planning, Scheduling, and Controlling. Wiley.
- This comprehensive guide delves into various project management methodologies, including a detailed analysis of percentage completion's limitations and the advantages of more robust methods.
Cleland, D. I., & Gareis, R. (2016). Project Management: Strategic Design and Implementation. McGraw-Hill Education.
- This text provides a detailed examination of project planning and control, emphasizing the importance of accurate progress measurement and the drawbacks of simplistic approaches like percentage completion.

Articles

"The Pitfalls of Percentage Completion" by David H. Olson, Project Management Journal, 2008.
- This article explores the inherent problems of relying on percentage completion for project progress measurement, highlighting its subjectivity and lack of accuracy.
"Why Percentage Completion is Not Enough" by Michael DeMarco, Project Management Institute, 2017.
- This article outlines the limitations of percentage completion and presents compelling arguments for using more robust methods like Earned Value Management for accurate progress evaluation.
"The Art and Science of Project Progress Measurement" by Jeff Sutherland, Scrum.org, 2019.
- This article delves into various methods for measuring project progress, emphasizing the importance of considering task complexity, resource availability, and work quality beyond simple percentage calculations.

Online Resources

Project Management Institute (PMI): https://www.pmi.org/
- PMI's website offers a wealth of resources on project management, including articles, research papers, and training materials related to project progress measurement and Earned Value Analysis.
Earned Value Management Association (EVMA): https://www.evma.org/
- EVMA is a professional organization dedicated to promoting Earned Value Management (EVM) principles and practices. Their website offers resources, training materials, and certification opportunities for EVM practitioners.
ProjectManagement.com: https://www.projectmanagement.com/
- This website provides articles, webinars, and other resources covering various aspects of project management, including in-depth discussions on progress measurement and Earned Value Analysis.

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