Project Management tries to gain control over five variables:
Time - The amount of time required to complete the project. Typically it is
broken down for analytical purposes into the time required to complete the
components of the project. This is then further broken down into the time
required to complete each task contributing to the completion of each component.
Cost - Calculated from the time variable. Cost to develop an internal project
is time multiplied by the cost of the team members involved. When hiring an
independent consultant for a project, cost will typically be determined by the
consultant or firm's hourly rate multiplied by an estimated time to complete.
Quality - The amount of time put into individual tasks determines the overall
quality of the project. Some tasks may require a given amount of time to
complete adequately, but given more time could be completed exceptionally. Over
the course of a large project, quality can have a significant impact on time and
cost (or vice versa).
Scope - Requirements specified for the end result. The overall definition of
what the project is supposed to accomplish, and a specific description of what
the end result should be or accomplish.
Risk - Potential points of failure. Most risks or potential failures can be
overcome or resolved, given enough time and resources.
Three of these variables can be given by external or internal customers. The
value(s) of the remaining variable are then set by project management, ideally
based on solid estimation techniques. The final values have to be agreed upon in
a negotiation process between project management and the customer. Usually, the
values in terms of time, cost, quality and scope are contracted.
To keep control over the project from the beginning of the project all the
way to its natural conclusion, a project manager uses a number of techniques:
project planning, earned value, risk management, scheduling and process