Lead, lag and CPM
The big idea
Scheduling
According to PMI a project is a temporary effort to create a value, by changing the status quo. It has an start date and an end date. In between them are some great pillars on which the project relies. One of those is the scheduling or planning management [1]. While scheduling can be done with various tools and methods, this article will focus the use of lag & lead both for scheduling and for purposes as Key Performance Indicators (KPI). As the purpose of this article is to investigate and show how scheduling could be optimized for project efficiency, some complementary methods will be included. These methods will be Critical Path Management (CPM) and Program(Project) Evaluation and Review Technique (PERT) to get a quantified take on possible scheduling risks that might be faced.
As a project consists of different activities that make up the change of status quo, these activities might be connected and some independent. Nevertheless, do we need to face which kind of interaction these tasks have in order to optimize the time schedule of the project.
When using lag & lead, the project activities will most often be sequenced. To get a understanding of the sequence, the precedence relations of the activities should be mapped. This could be done by the use of CPM-, PERT-, and network diagrams. The PERT and CPM holds some more data and assumptions which will be discussed later. Those can be seen as iterations of the more simpler version, namely the network diagram that shows the precedence relation between actions (sæt springer kilde ind, side 18). For the purpose of this article, the precedence network will form the basis (indsæt evt. kilde der samler op på PMBOK).
Research in scheduling has grown ever since its start in the late 1950’s. CPM and PERT being the main focus back then, means that they have undergone severe development. As a consequence further theories and iterations have been based on mathematics (springer preface). To grasp the concept of lag & lead, the computerized methods developed should be to far over the aim for this article.
