Let's say the dates are in column A, the y-values in B
In column C type a 1 next to the cells you want plotted
In D2 (I will assume the first row has headers) , enter =IF(D2=1,B2,NA())
Now select all the D data and copy it; click on the chart, use Edit | Paste
Special to copy the data as a New Series
Now format the new seresi to have the came colours etc as the original
series
Add a trend line to the new series
You can now change the data in C to get trendlines for other regions
best wishes
--
Bernard Liengme
http://people.stfx.ca/bliengme
Microsoft Excel MVP

"aarho" wrote in message
...
I perform a lot of tests that involve changing changing an element during
the
run and observing the effects over time and it would be extremely useful
if I
could create a trendline that covered only the desired range of data,
rather
than spanning the entire chart, without having to go in, find the data
range
and plot it in a chart of its own. Is there any way to do this?

I'm currently using Office 2003.