Duration, ES, EF, LS, LF & Slack inconsistent calculation

[kdwoell]

My project settings in Project 2003:

Calendar- I modified calendar "nigh shift"; working hours 7-10pm M-F
and 5-10pm Sat-Sun
Task type- globally assigned "Work Fixed"
Logic- summary tasks are shells with no logic attached to them.
Ensured there are no constraints or resources assigned to the summary
tasks. Linked everything, assigned resources and globally assigned "As
Soon As Possible" constraints all at the sub-task level.

Problem:
I'm not confident with LS & LF dates calculated by Project. Nor am I
confident with the slack calculations. "Free Slack" is the attribute
in Project which seems to be the closest to the idea of "float" we use
in a course I'm taking. Here are several examples of where I get
conflicting slack (float) calculations:

WBS ID 20= Pack Living Room- first issue, I manually calculate a float
of (ES-LS) 15dys, and (EF-LF) 16dys? No agreement. Second issue,
Project returns slack of 6.12dys? Totally different?
(ES-LS) 15dys, and (EF-LF)

ES 2/27/2008 EF 2/28/2008 98.00dys
LS 6/4/2008 LF 6/4/2008 97.00dys

WBS ID 66= Test new property keys- first issue; I manually calculate a
float of (ES-LS) 98dys, and (EF-LF) 97dys. No agreement. Second issue
Project returns a slack of 6.19dys. Totally different?

ES 2/16/2008 EF 2/18/2008 15.00dys
LS 3/2/2008 LF 3/5/2008 16.00dys

Note:Excel used calculate the days manually.

Any help appreciated.
-kw

 

[DavidC]

Hi,

Have you set the options under "Tools/calendar" to refelct the change in the
calendar?

Microsoft does all its calculations from those settings. Hence a day is by
default 8 hrs per day 8am to 5pm.

Do you modify the standard calendar to incorporate the night shift, or is
the night shift another calendar again? What calendar is used as the Project
calendar?

Are you lookign at "Free Slack" that period between the late start of the
predecessor and the early start of the successor, or are you looking at
"Total Float" which calculates across the whole task sequence.

 

[kdwoell]

Hi,

Have you set the options under "Tools/calendar" to refelct the change in the
calendar?

Microsoft does all its calculations from those settings. Hence a day is by
default 8 hrs per day 8am to 5pm.

Do you modify the standard calendar to incorporate the night shift, or is
the night shift another calendar again? What calendar is used as the Project
calendar?

Are you lookign at "Free Slack" that period between the late start of the
predecessor and the early start of the successor, or are you looking at
"Total Float" which calculates across the whole task sequence.













- Show quoted text -

Under Tools-Options-Calendar: the "nighshift" calendar is shown as the
one in use. Settings:
Week starts on: Sunday
Fiscal year: January
Defautl start time: 8am
Defautl end time: 5pm
hours per day:8.0
hours per week: 40
days per month: 20

However, I have used the Change Working Time command to modify the
calendar as sated in the first post. Two human resoruces are assigned
to the project and they use the Nighshift calendar. And just to be
sure, I mathced their individual working hours to those of the
Nightshift calendar. Here is a cut/paste from my project file for WBS
ID=20

pack living room 14 hrs (work), 0.98 days?(duration), $840.00 (cost),
Fri 2/15/08(ES), Sun 2/17/08 (EF) , Sat 3/1/08(LS), Mon 3/3/08 (LF),
6.93 days?(start slack), 6.93 days? (finish slack), 0 days?(free
slack), 6.93 days?(total slack), No (critical), As Soon As Possible
(constraint)
There are two resources assigned to this task, both are available
%100. My numbers differ now from the first post since I gloablly
changed all tasks to "fixed units" w/effort driven. I double checked
all tasks. Each has a predecessor/successor. All link types were set
to FS (even though thats not realistic in some cases).