ExcelBanter - how to draw a trendline using two set of data?

Do you want two trendlines, one for each data set? The Add Trendline dialog
(Chart menu Add Trendline) has a listbox to allow selection of a series.

Do you want to combine the data into one series? You need to define a series
that contains all of the points. If your two separate series have these
series formulas:

=SERIES(Sheet1!$C$4,Sheet1!$B$5:$B$12,Sheet1!$C$5: $C$12,1)
=SERIES(Sheet1!$D$4,Sheet1!$B$5:$B$12,Sheet1!$D$5: $D$12,2)

you need to add a series with this formula:

=SERIES("Combined",(Sheet1!$B$5:$B$12,Sheet1!$B$5: $B$12),(Sheet1!$C$5:$C$12,Sheet1!$D$5:$D$12),3)

Note how you can define multiple area ranges by separating the areas with
commas and enclosing the combined range in parentheses.

You can simply select the plot area, then click in the formula bar, and type
or paste in a valid formula like this.

- Jon
-------
Jon Peltier, Microsoft Excel MVP
Tutorials and Custom Solutions
http://PeltierTech.com
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"PY" wrote in message
...
Dear All,
How to draw a trendline using two set of data (same x-value but different
in
y-value)

thanks
Cheers