Creating Linear Trendlines for Certain x ranges in a Graph

Hi,

I'm new to both this forum and Excel 2007 (for Windows). What I'm trying to do is add a trendline to specific parts of a graph, but not to the graph as a whole. I have the graph on a separate sheet labeled Chart 1. It is a scattergram of concentration (ppm) as a function of time (from 0:00:00 to 1:21:15 in increments of 5 seconds). I want to add a trendline from 0:00:00 to 0:09:52, from 0:09:52 to 31:00, from 31:00 to 1:01:01, and from 1:01:01 to 1:05:57. How should I go about doing this? Sorry, I'm a beginner.

Extra (Helpful) Info:
On the Chart1 sheet, on the functions tab it says:

=SERIES(Sheet1!$C$10,Sheet1!$B$11:$B$986,Sheet1!$C$11:$C$986,1)

Starting from A11 (label is at A10) to A986, is the time in H:M:S. B11 (label at B10) to B986 is the time passed starting from 0:00:00. C11 (label at C10) to C986 is the concentration.

Sometimes, I get the message near the ribbon that says: Security Warning: Data connections have been disabled.

^ Thanks. It worked perfectly!

I added to your rep.

Hi, I am using Excel 2010 (Windows) and trying to do something similar. I have three data series, one "total" and then two sub-sets. The time period (Axis labels) runs from July to May. The two sub-sets only have data from January to May. However, in order to have them appear on the graph in their correct spot I have to have series data run from July to May, including the blank cells, otherwise the Jan-May data points show up intermingled with the July-November data points (Excel wants every data series to start on the far left, period). That's OK and is not the issue. The issue is that when I create a trendline for the sub-set data the trendline runs all the way from the far left to the far right of the graph. My customer would prefer those trendlines only appear from January-May. Is there some way that I can tell the trendline, "Start here, not there?"

Hello deanslgr, and welcome to the forum.

Unfortunately you have inadvertently broken one of the forum rules. Please read the following and make the necessary change. Thanks.

Your post does not comply with Rule 2 of our Forum RULES. Don't post a question in the thread of another member -- start your own thread. If you feel it's particularly relevant, provide a link to the other thread. It makes sense to have a new thread for your question because a thread with numerous replies can be off putting & difficult to pick out relevant replies.

I'm glad that makes sense to you.