IBM System Dashboard for ECM. Average Response Time - what's this?

Last two weeks I have to recall a programming because we need to monitor some production FileNet environment. I write some reporting system what use an information from IBM System Dashboard for ECM. I think, it is rather useful utility and can be a solid basis of some simple monitoring system.

Unfortunately, I had to explore algorithms of counting of  parameters and a compliance of parameters myself.

One of very important parameters what was asked our customer is Average Response Time for ECM servers. Who saw System Dashboard must know - these graphs are shown on its main page. I had to build the same graphs using my BIRT.
But there were no any parameters named "Response Time" in the list of server parameters.

I asked IBM Support Team. One guy answered me that it looks like a server's ping :)

I had to explore a compliance. And I was very confused when I discovered that "Average Response Time" is "MarkSweepCompact duration" in reality :) No any difference, really?

"Average Response Time" from System Dashboard.

"MarkSweepCompact duration" in metrics

 
 
 
My graph of "Average Response Time" :) (or "MarkSweepCompact duration") for Workplace separately.