Statusing Best Practice

[JR]

Is there a statusing best practices or guidelines available anywhere?

The following are a couple of questions I have regarding statusing
methods and the effect each method might have on critical path
calculations:

1) Task A is a predecessor to Task B. Task A has completed but Task B
cannot start right away. Which is the better method to offset Task B
to the estimated start date:
a) Set a "Start No Earlier Than" date constraint
b) Increase the lag of Task B

2) What are the effects of each method in Question #1 to the total
slack calculation?

Thanks!
J. Rodrigo

 

[Steve House [MVP]]

Giving you a very definitive asnwer .... it depends! <grin> You need to
ask WHY task B can't start right away. Parts not here? Resource tied up
elsewhere? Waiting for a client or government approval? If it was
something like parts not in or unable to get access to a site before a
certain date, I'd say a SNE constraint. If it was resource conflicts, I'd
use resource leveling to establish the delay or input a manual delay in the
resource schedule form of the split screen if it was caused by him being
tied up on something outside the project. If it was waiting for an
approval, I'd use the lag time. I see the project plan as a predictive
model - while there are several ways to delay a task and they may all have a
similar bottom line effect on the task's dates, I like to try to make sure
the plan is as an accurate a model of the process as possible.

 

[JR]

Thank you for your answer! I've heard the same kinds of arguments from
others. It's my opinion that when you use a lag time to offset a task
that it should mean something. For example, when you paint a wall with
primer you have to account for drying time. In that case, I would
either use a lag to represent the drying time or simply put in a task
to represent the drying time. An unforeseen delay should be offset by
a SNET constraint. By doing this, you could (conceivably) use this
schedule as a template for future use by simply removing the
constraints. (NOTE: We do not adjust resources to drive the schedule
because it can just get too messy to track. Our assumption is that we
have unlimited resources.)

I've been told that I should adjust the lag to offset the task. It is
believed that offsetting a task any other way will result in a total
slack calculation error. I do not believe this to be true except for
tasks that use hard constraints (MSO or MFO).