With activities on arrow (AOA) diagrams, you are limited to showing only the finish-to-start relationships - that is, the arrow can represent only that the activity spans the time from the event at the start of the arrow to the event at the end. As well, "dummy" activities have to be added to show some of the more complex relationships and dependencies between activities. These diagrams came into use in the 1950's, but are now falling into disuse.
Activity on node (AON) diagrams place the activity on the node, and the interconnection arrows illustrate the dependencies between the activities. There are more flexible and can show all of the major types of relationships. Since the activity is on a node, the emphasis (and more data) usually can be placed on the activity.
AOA diagrams emphasize the milestones (events); AON networks emphasize the tasks.
Introduction to The Nine Project Management Knowledge Areas
Also read about our new agile delivery model called Scrumthat is significantly different than the model below. As a PMP I often get questions about what goes into running a project. I will try to explain in a couple of articles the various components that make up a project. There are several ways to look at a project as a whole. You can view it as a series of processes. Some processes are executed in order and some are recurring processes that are executed at various stages throughout the entire project. You can also view the project from the different knowledge areas that are needed to execute the project. I will cover the knowledge areas in this article and go on to the processes in my next article. There are nine knowledge areas and each one covers its own important part of the project. A knowledge area can cover several phases or process groups of the project. The nine areas are mentioned below in some detail. Integration Management
If each little part of the project is a tree, Integration Management is the entire forest. It focuses on the larger tasks that must be done for the project to work. It is the practice of making certain that every part of the project is coordinated. In Integration Management, the project is started, the project plan is assembled and executed, the work is monitored and verification of the results of the work is performed. As the project ends the project manager also performs the tasks associated with closing the project. A project manager must be very good at Integration Management or the project may very well fail. Other knowledge areas are also important, but Integration Management is the area that requires the most management and control of the entire project. Scope Management
This area involves control of the scope of the project. It involves management of the requirements, details and processes. Changes to the scope should be handled in a structured, procedural, and controlled manner. The goal of scope management is to define the need, set the expectations, deliver to the expectations, manage changes, and minimize surprises and gain acceptance of the project. Good scope management focuses on making sure that the scope is well defined and communicated very clearly to all stakeholders. It also involves managing the project to limit unnecessary changes. Time Management
Project Time Management is concerned with resources, activities, scheduling and schedule management. It involves defining and sequencing activities and estimating the duration and resources needed for each activity. The goal is to build the project schedule subsequently to manage changes and updates to the schedule. When the schedule is first created, it is often referred to as the time baseline of the project. It is later used to compare updated baselines to the original baseline. Many project...