Why in MS Project when I assign a percentage to the resources, it does not change the finish date accordingly.

I assigned a resource 50% in Units column. When I set duration to 1 day it does not calculate finish date accordingly. How can I set up the project such that, when I set percentage allocation on a resource, and the duration and start date, finish date adjusts accordingly.
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Richard DanekeTrainerCommented:
Project assumes that the duration set in creating the task is the correct or proper duration.  
Therefore, when you assign a resource at 50% for a one day scheduled task, Project assumes the duration was correct and no adjustment is made.
However, if you had assigned a resource at 100% for a 1 day duration, project would have made the same assumption and left the duration at one day.  Now, change the resource to 50% for the task and Project will adjust the duration.

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In addition to Richard's comment:-
 project takes into account which type of task you have setup - this can be changed on the advanced tab of the task information dialogue

Fixed duration means it will take a specific length of time to complete: (for example: the lead time from a supplier is generally fixed). you can change the number resource units assigned and  the amount of effort will be adjusted or change the amount of effort and the resource units will change.

Fixed work means that the effort needed will be the same regardless of duration (eg: digging a hole will take the same total amount of work if you do it in one day or spread it over three days) - change the number of resource units assigned and duration will change, change duration and resource units will change

Fixed Units means that the number of people working on the task is always fixed - so you can change the effort and the duration will be modified or change the duration and effort will be changed

When you put 1 day duration and assigned someone 50% Project assumed  that that would be enough to complete it in that time.

Your confusion is because you are trying to treat 'duration' as 'man days' when its actually the elapsed days between start and finish - and, obviously, you can have a lot of people working full time on a task or one person working part time.
OK, and another comment....
MS project calculate all the time with work, not duration, nevertheless, the column is not visible by default. Also it is a difference if you add a resource the first time or if you change the resource later.

The basic rule is...
work = duration * units
If you assign a resource the first time, the missing element is calculated (doesn't matter how the task is set up). If you have planned a task with 10 days, and you assign a resource with 50% (0,5 units), MS Project calculated the missing the work, so the rule is...
work = 10 day * 0,5 units = 5 days
Nothing changes at this step.

If you then change one of the values work, duration or units, it depends from the setting "fixed work", "fixed duration" or "fixed units". The "fixed" value stays as it is for all changes on the other values. If you change the "fixed" values, MS Project changes the duration, or if it is "fixed duration" the work.

The easiest way to understand these relation sis just to insert the column "work" and to play around with the "fixed" settings.

The major misinterpretation is, that you see duration and units, but not the work. If you work with resources, the work is the driving element. For serious project management, a task is always calculated (and charged) by work on not the duration. To underline the point of view is just the fact, that a job can take 4 weeks, but there are only 2 days of real work. The work is the charged value (2 days)  and the duration of 4 weeks is just the time frame, when the work can be done.

All values in MS Project are only driven by the work value, not by the duration value.
No comment has been added to this question in more than 21 days, so it is now classified as abandoned.

I have recommended this question be closed as follows:

-- Richard Daneke (https:#a41187010)
-- regmigrant (https:#a41187644)
-- Bembi (https:#a41211145)

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