Crashing - incrementally or in chunks?
This concerns Coursework 2, "Berry and Partners".
Student S quoth:
Hmm, there may be some cake left in the tin still in the runny state.
We are not saying that it's never possible to ever consider crashing activities in this way. We are simplifying the planning task by constraining the tasks to be either one of the two options given. The intention is to make the coursework easier to do.
Busy people can stop reading now, but there's more explanatory goodness ...
In reality, it is often very difficult to make accurate assumptions about the cost/time slope in between two known points. Managers often assume (you know, an ASS out of U and ME) that by, say adding more people to a task, that they can controllably reduce the duration by whatever factor they choose. Wise commentators will be wafting themselves with their copies of "The Mythical Man-month" at this point, before fainting.
Usually any reduction in time is not in some straightforward ratio of the people added to the numbers already used. Often, there are non-linearities or overheads in the work process that break such clear relationships. An example: four people work in a mechanical workshop using machine tools. All the tools are occupied by the present work. Adding a fifth person will not add capacity to the workshop without providing a fifth tool. Even if a tool is provided, the fifth person may not be as familiar with the project tasks and their work rate could be lower.
Sometimes, the addition of personnel results in an increase of task duration. More people, more arguments ...
In our view, it is better to identify clear options for task time and duration (which may or may not involve more people -- more likely a different work process or technology will be involved) and to manage the plan using these options. For certain tasks, a continuous range of options is available, though we think these will be the exception.
Student S quoth:
it said "Activities can only be 'crashed' to the blocks of time given
in the table, and not incrementally on a week-by-week or day-by-day
basis."
I did a course entitled 'Management for Engineers' 2 years ago at
the Dept. of Mechanical Engineering and the lecturer specifically
said that it is incorrect to crash activities to their crash duration
at one go and these need to be done incrementally, i.e. reduce the
project duration 1 week at a time.
Hmm, there may be some cake left in the tin still in the runny state.
We are not saying that it's never possible to ever consider crashing activities in this way. We are simplifying the planning task by constraining the tasks to be either one of the two options given. The intention is to make the coursework easier to do.
Busy people can stop reading now, but there's more explanatory goodness ...
In reality, it is often very difficult to make accurate assumptions about the cost/time slope in between two known points. Managers often assume (you know, an ASS out of U and ME) that by, say adding more people to a task, that they can controllably reduce the duration by whatever factor they choose. Wise commentators will be wafting themselves with their copies of "The Mythical Man-month" at this point, before fainting.
Usually any reduction in time is not in some straightforward ratio of the people added to the numbers already used. Often, there are non-linearities or overheads in the work process that break such clear relationships. An example: four people work in a mechanical workshop using machine tools. All the tools are occupied by the present work. Adding a fifth person will not add capacity to the workshop without providing a fifth tool. Even if a tool is provided, the fifth person may not be as familiar with the project tasks and their work rate could be lower.
Sometimes, the addition of personnel results in an increase of task duration. More people, more arguments ...
In our view, it is better to identify clear options for task time and duration (which may or may not involve more people -- more likely a different work process or technology will be involved) and to manage the plan using these options. For certain tasks, a continuous range of options is available, though we think these will be the exception.
posted by Matt at
13:40
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