C
Chris Baker, Freelance Project Manager
I have been trying to get more of a feel for the distinction s between MS
Project task types (Fixed units, fixed work, fixed duration). I understand
that Project uses the equation duration= work/units, and the fixed bit is
which of these parameters Project isn't allowed to adjust (e.g. in a fixed
duration task, if you adjust work, Project assumes that it needs to adjust
units). This is all very well, but I feel the need to have a few examples to
make this real for me. So I have made some up and I'd be grateful if you
would check whether I have got this right (it is, I now a famously tricky
concept to get hold of or to teach):
Fixed units task (the default type): the traditional "lump of labour": a
certain number of man-hours work that can be done in less time with more
resources Examples
1) a report needs to be typed
2 a wall needs to be painted:
two workers will have the job finished in half the time (but will have done
the same amount of man-hours during that time as one worker working alone).
Fixed duration: something that just takes a certain amount of time,
regardless of how many people work on it. The effort of doing it can't be
shared out in such a way that more people do less work each. Examples:
1) Paint or concrete drying
2) You send a report around to the team, and give them 5 days to read and
give feedback - everyone needs the 5 days, you won't be reducing the deadline
if more people need to read the report.
3) The team have to travel to a meeting - the journey and meeting take the
time it takes (sadly you can't get the journey or the meeting to be shorter
by sending more people; usually it is the converse!)
Fixed work (Achtung! I'm less certain whether I have this right): A task
that people can share out that time in various ways, but with some other
factor than the people determining how long it takes : Examples:
1) Several people work on a task but they need to share equipment (e.g. you
have 5 people to dig, but only one spade). Adding more people won't make the
task go quicker, because it is the equipment that is rate-limiting. But if
you add more people, they will each work less on the task.
2) A white-collar example: the team have to staff a stall at a trade fair.
The trade fair is open for a certain amount of time and is not over sooner if
you send more staff. If you send one person, she will need to be on the stand
all day without breaks. If you send several workers, you COULD do so on the
basis that they all mind the stand (you could do that as a fixed duration
task in that case) OR you could have them take turns minding the stand and
spend the rest of the time doing other work (fixed work). Send 5 workers and
you can tell MS Project that they are all working 20% on the stand, and it
will allow them to spend 80% of the day spying on the opposition, schmoozing
potential customers or doing other work. If it is announced that the trade
fair will open an extra day (i.e. it's duration is increased) your team will
ahve to share out the extra hours somehow (more units for everyone, unless
you send a larger delegation).
3) I THINK that you might also use this task type if health and safety or
other considerations limited the number of hours that a worker could do -
e.g. only allowed to drive for so many hours.
Is that right? And how does teh "Effort driven" checkbox come into this?
Project task types (Fixed units, fixed work, fixed duration). I understand
that Project uses the equation duration= work/units, and the fixed bit is
which of these parameters Project isn't allowed to adjust (e.g. in a fixed
duration task, if you adjust work, Project assumes that it needs to adjust
units). This is all very well, but I feel the need to have a few examples to
make this real for me. So I have made some up and I'd be grateful if you
would check whether I have got this right (it is, I now a famously tricky
concept to get hold of or to teach):
Fixed units task (the default type): the traditional "lump of labour": a
certain number of man-hours work that can be done in less time with more
resources Examples
1) a report needs to be typed
2 a wall needs to be painted:
two workers will have the job finished in half the time (but will have done
the same amount of man-hours during that time as one worker working alone).
Fixed duration: something that just takes a certain amount of time,
regardless of how many people work on it. The effort of doing it can't be
shared out in such a way that more people do less work each. Examples:
1) Paint or concrete drying
2) You send a report around to the team, and give them 5 days to read and
give feedback - everyone needs the 5 days, you won't be reducing the deadline
if more people need to read the report.
3) The team have to travel to a meeting - the journey and meeting take the
time it takes (sadly you can't get the journey or the meeting to be shorter
by sending more people; usually it is the converse!)
Fixed work (Achtung! I'm less certain whether I have this right): A task
that people can share out that time in various ways, but with some other
factor than the people determining how long it takes : Examples:
1) Several people work on a task but they need to share equipment (e.g. you
have 5 people to dig, but only one spade). Adding more people won't make the
task go quicker, because it is the equipment that is rate-limiting. But if
you add more people, they will each work less on the task.
2) A white-collar example: the team have to staff a stall at a trade fair.
The trade fair is open for a certain amount of time and is not over sooner if
you send more staff. If you send one person, she will need to be on the stand
all day without breaks. If you send several workers, you COULD do so on the
basis that they all mind the stand (you could do that as a fixed duration
task in that case) OR you could have them take turns minding the stand and
spend the rest of the time doing other work (fixed work). Send 5 workers and
you can tell MS Project that they are all working 20% on the stand, and it
will allow them to spend 80% of the day spying on the opposition, schmoozing
potential customers or doing other work. If it is announced that the trade
fair will open an extra day (i.e. it's duration is increased) your team will
ahve to share out the extra hours somehow (more units for everyone, unless
you send a larger delegation).
3) I THINK that you might also use this task type if health and safety or
other considerations limited the number of hours that a worker could do -
e.g. only allowed to drive for so many hours.
Is that right? And how does teh "Effort driven" checkbox come into this?