Which came first?

Which came first?


I am trying all kinds of methods to prepare for the PMP exam that I plan to take in June. With the lengthy workbooks, Global Knowledge has provided me with audio CD’s to reinforce the concepts while I am driving in my car or listening on my back deck.  I have listened to disc 1 and 2 until I am sick to death of the commentator’s voice. He has a sleepy voice that doesn’t help.  I start disc 3 this week.  I think it is reinforcing concepts but I find myself easily distracted so I know I am not an auditory learner by nature.  The more variety of methods of processing the information for me is a help.  My 50 plus year brain is not as stretchy as it used to be.

So, I am studying the Knowledge Area of Project Time Management this afternoon (the T in The in the mnemonic I Saw The Car Quickly Hit Chelsea’s Righteous Poodle Squarely…remember?)

One of the processes we have to understand under time management, is how to sequence activities.  The definition is the process for identifying and documenting relationships among the project activities.  The key benefit is that it defines the logical sequence of work to obtain the greatest efficiency given all project constraints.  One of the tools to use to sequence activities is the Precedent Diagramming Method (PDM).  Activities are graphically represented as nodes and linked by logical relationships to show the sequence in which the activities are performed.  A fancy term for the activity is called Activity-on-nod (AON) which simply represents the activity on the diagram.

Let’s discuss logical relationships and four types of dependencies.   Does this sound like something Dr. Phil would say?

Must learn this– a predecessor activity is an activity that logically comes before the dependent activity in the schedule.  A successor activity is a dependent activity that logically comes after another activity in a schedule.  PDM includes four types of dependencies that we need to understand and use in the exam.

Predecessor – to – Successor (this is the order to keep in your mind for below)

  • Finish-to-start (FS) — successor can’t start until predecessor is finished.
  • Finish-to-finish (FF)successor activity can’t finish until predecessor is finished.
  • Start-to-start (SS)successor activity can’t start until predecessor has started.
  • Start-to-finish (SF)successor activity can’t finish until predecessor activity has started.

Finish-to-start is commonly used in sequencing activities.  For example, you have to mix all the ingredients for a delicious red velvet cake (predecessor) before you put the yummy goodness in the oven (successor).

Finish-to-finish is common in grant writing as we have to write the proposal (predecessor) before the editing team comes in to edit (successor).

Start-to-start is common in construction in which the electricians (successor) can’t begin to run electrical wire until some of the framers have started to put up the internal walls (predecessor).

Start-to-finish is common in scheduling shift staff at a work site.  The first front desk clerk (successor) can’t go home until the second desk clerk (predecessor) shows up.

We sequence activities in our mind all the time.  Before we leave to run errands, we think about the most efficient ways get our stops completed and back home.  Do you go to the grocery store before you deposit your pay check at the bank?  Probably not.  Do you pick your poodle up from the groomers first in the list of eight other errands you have to complete?  Probably not.  At home, do you wash the car in the front driveway and then use the grass blower to clean up the front porch?  Probably not.  Think of times you messed up on sequencing at home or at work and what ramifications it had for efficiencies.



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