Duration Units changed after entering work hours

[Tom]

Durations that I had set for each task has changed after I assigned work
hours to the task. Example: before assigning work hours, task A = 3days.
After assigning 4 hours of work to Task A, duration is now 2.94days. I am a
novice user. My understanding of work and duration is: duration is length of
time for a task to get completed, work is the actual amount of time for a
resource to complete task. For example, it may take a few days of phone-tag
to get someone on the phone for a conversation that only lasts a few minutes.
So duration would be the required number of days and the work would be the
time it took to completeion each call attempt.

Question is: Does assigning work hours to task change the duration? And, is
my understanding of work and duration correct?

 

[Steve House [Project MVP]]

Your understanding is close - duration is the time between when work first
takes place and when it ends, work is the amount of effort that is expended.
Note the idea of time betwwen start and finish - If I assign you to do 4
hours of work on a task that could start any time now (this being Wed) and
is due by Friday afternoon and whenever you get started you'll devote your
full attention to it until it is done, that task is a 4 hour task not a 3
day task. On the other hand, if you have to divide your attention with
something else, working on both of them together, the 4 hours of work will
require 8 hours duration to complete. Now, the big question in my mind
right off the bat is just how did you designate the work? "Work" is more or
less a meaningless notion unless a resource is assigned to the task. You
can say "I expect this to require 4 man-hours of work" but you can't really
relate that to the task duration until you also know how hard the resource
assigned is working. The change from 3 days to 2.94 days seems likely to be
related to the calendar controlling the task but we need a little more
information about your scenario to pin it down farther than that.