4.13. PROJECT DYNAMICS There are a variety of activities, from writing term-papers to building nuclear power plants, that have very similar dynamic characteristics. There is a goal and an expectation of what it takes to achieve the goal, followed by lots of work, followed after some period of time by a more or less successful achievement of the goal. Projects that, relative to the initial goals and expectations, take too long, cost too much, have poor quality, and complete too little are common. In this exercise we will develop a model to help understand the processes involved in getting a project done. For concreteness we will think of this project as the design of a new building, though the model is directly applicable to other activities such as developing software, designing a new product, preparing a presentation and writing an exercise. The model would need to be extended to investigate activities such as construction in which material availability becomes very important, or scientific research in which experimentation plays a key role. In conceptualizing and creating this model we will use an iterative approach. We will start with the simplest structure that is relevant to this problem, and continually refine it. This is a useful technique because it prevents a situation in which you feel you have completed a model, but the situation results simply do not make sense. You will be simulating a every step, and seeing the effects of new model structure as it is added. In developing this model we will be depending on the computer to continually give us feedback on the consequences of changing structure. While the computer is very good at this, it is also important to think about what we are doing. Before any simulation experiment is run you should ask yourself what you expect the results to be. If you are surprised find out why. If you are right make sure it is for the right reasons. Model 1. Task accomplishment. The most fundamental characteristic of any project is that there is something to do and it gets done. Model 2. Stopping Work There are some ways to shut down the project model. One simply to stop simulating when the project is done, other one is to create a variable 'project is done' to control this. This last way will provide us with a mechanism for descoping the project if there are schedule or budget problems. Model 3. Errors and Rework So far we have assumed that the work being done is being done without error. In general this is not true. There are a number of places where errors can occur, including miscommunication among personnel, technical oversights and just plan mistakes. When errors occur they are not, however, immediately discovered. Errors remain undetected until there is a review or integration activity that brings them to light. Model 4. Rework Discovery The final stages of a project tend to see a big increase in rework discovery. It is very much like finally putting the pieces of a puzzle together. At the end it becomes quite obvious which pieces are missing or the wrong shape. Example of problems that can occur are plumbing systems that depend up nonexistent access corridors and ventilation shafts that are the wrong size for the planned equipment. Model 5. Schedule The purpose of project management is to keep projects on schedule. To do this it is necessary to know what the schedule is, and adjust resources to meet that schedule. LINKS: Theory and Practical Exercises of System Dynamics System Dynamics Online Courses Building Models in Ecology Building models with Vensim Other resources in System Dynamics Boletín de Dinámica de Sistemas