What is the difference between Lag,Delay&Free Slack?

[subzizo]

When Scheduling project i can add lag time between two tasks or add free
slack or delay the successor task and in all situation a duration of time is
add between the finish of the first task & the start of the second .....what
i want to ask here what is the difference between these methods ??What are
the actual effects of each method?

[Gérard Ducouret]

Hello Subzizo,
Lag : you can introduce a 3 days (or better : 3ed : elapsed duration) lag
time between the task "1st painting coat" and "2nd painting coat" because
the
the painter told you that you have to wait 3 days for paint drying. In the
Predecessor column, you'll write 10FS+3ed if the "1st painting coat" task
is on the row n° 10.
Delay : The leveling feature of MS Project may introduce a "Delay" of 5 days
if one task was in conflict with another one because they use the same
resource while the 2 tasks overlap during 5 days. You can show the "Leveling
Delay" in the Delay table.
Try Tools / Level Resources... / Level Now and look at the Leveling Gantt
view.
Free Slack : you can't add any Free Slack : Ms Project calculate it. That's
the duration between the Early finish of the task and the Early Start of its
earlier successor. You can show the Free Slack in the Schedule table.

Hope this helps,

Gérard Ducouret [Project MVP]

Post by subzizo
When Scheduling project i can add lag time between two tasks or add free
slack or delay the successor task and in all situation a duration of time is
add between the finish of the first task & the start of the second .....what
i want to ask here what is the difference between these methods ??What are
the actual effects of each method?

[Haris Rashid]

hi,

For linked tasks, lag defines the "delay" between the linked tasks. Fro
example, consider painting a wall and hanging a picture frame. You can add a
lag to the "hang picture task" because it cannot start on completion of just
painting task. The paint needs to dry before you attempt to hang the picture.
It is in this sence that you will add a lag time. Lag time essentially
changes the start of the successor task by delaying it. However on the plan
you won't call it a delay because the schedule will show the gap and a later
start of the task to hang the picture. You may think of lag as a planned
delay.

A true delay on the other hand is the actual amount of time that the task is
behind schedule.

Free Slack is the amount of time that a task can be delayed without delaying
its successor tasks. For a task without successors, free slack is the amount
of time that the task can be delayed without delaying the finish date of the
project.

Regards,

Haris.
------

Post by subzizo
When Scheduling project i can add lag time between two tasks or add free
slack or delay the successor task and in all situation a duration of time is
add between the finish of the first task & the start of the second .....what
i want to ask here what is the difference between these methods ??What are
the actual effects of each method?