Start/Finish vs Schedule Start/Finish vs Actual Start/Finish

Question

Hi,
I'm new to MSP 2013 and I'm confused on the way MSP handles Start/Finish dates. While I understand the rational of it adjusting the schedule so you see how actual dates impact the schedule, I find it confusing that there are multiple columns with different
labels performing the same function?
"Scheduled Start" would lead you to believe this is your initial planned start date and remains static while "Actual Start" would be, well, the Actual Start date. So one value by definition would be different than the other, yet when any
of these dates, "Scheduled Start", "Actual Start", or "Start" are changed, they all change to the same value.
My questions are:
Why do the "Scheduled Start", "Actual
Start", and "Start" dates all change to the "Actual Date" when entered?
Is there a scheduling technique or purpose for this to work this way?
Also, since the "Scheduled Start" date changes, how does MSP 2013 handle Earned Value?
       Since Earned Value calculations rely on your Planned Value which would be based on the Budgeted Cost of Work Scheduled          and the Earned Value which is
the Budgeted Cost of Work Performed vs. the Actual Cost of the Work Performed at "a point          in time," how could it provide a reliable figure if the scheduled date is moving? Is it using the "Baseline Start/Finish"?
I hope you can answer this for me or direct me to a resource that can. Thank you for your consideration.
Marc      

Answer 1

Marc,
When Project was first released there were only two basic start field, Start and Actual Start (in addition of course to the Baseline Start field and a few others). With the release of Project 2010, a manual scheduling mode was introduced. That's when things
got a little more confusing. Instead of leaving the Start date as is, the Start field was converted to a text field and the old Start field was renamed as Scheduled Start. When in auto-schedule mode, both Start and Scheduled Start are exactly the same.
Now to answer your questions. To keep it simple, let's assume you are using auto-scheduling.
1. In order to keep the schedule dynamics intact, it is necessary to update the Start field to agree with what really happened, namely with the Actual Start date. If you do not enter anything into the Actual Start field, Project automatically assumes the
task started as scheduled, on the Start date.
2, Yes, Project does its scheduling based on the current plan which is represented by start, finish and other data. Once the project starts, that current plan must be updated so the actual date values come into play. As noted in the lead in paragraph, Scheduled
Start and Start are the same for auto-scheduled tasks.
3. Earned value is based on the actual values and the saved baseline data. The "point in time" you refer to is the timescaled data as of the status date.
Hopefully, this clear up at least some of your confusion.
John