Dear Excel Experts: I have created a scatter chart of x and y values.
Having done this, is it at all possible to extract intermediate values from
the chart. For example, can I call out a value on the x axis and somehow
have the program interpolate a value along the y axis where the x axis value
would intersect. If this can't be done, then can someone tell me how to
interpolate from the data that was used to create this chart? Here's what I
have: the x axis is a series of values that represent rainfall storm
duarations in minutes, i.e. 10 min, 30 min, etc. The y axis values are the
intensity of the storm, i.e 1 inch, 3 inches, etc. Somehow, either with the
chart or data table, I need to interpolate for storm durations that I put in.
In simpler terms, if I put in say 12 min., (data for 10 and 15 are in the
table), I need to find out what the intensity is by interpolatation. To
further complicate matters, I need this interpolated value to go in a cell in
different parts of my spreadsheet.

Hello, BuickGN87!
You wrote on Thu, 5 Oct 2006 08:16:03 -0700:

B Dear Excel Experts: I have created a scatter chart of x and
y
B values. Having done this, is it at all possible to extract
B intermediate values from the chart.

I'm not convinced about the real validity of interpolated values
using measured data unless you have evidence that there really
must be an underlying equation. However, GROWTH will interpolate
(as well as extrapolate as the name might imply) and that might
be your best technique. There are also many formulas to
interpolate using two or more values, for what they are worth.

James Silverton
Potomac, Maryland

E-mail, with obvious alterations:
not.jim.silverton.at.comcast.not

"BuickGN87" wrote in message
...
Dear Excel Experts: I have created a scatter chart of x and y values.
Having done this, is it at all possible to extract intermediate values
from
the chart. For example, can I call out a value on the x axis and somehow
have the program interpolate a value along the y axis where the x axis
value
would intersect. If this can't be done, then can someone tell me how to
interpolate from the data that was used to create this chart? Here's what
I
have: the x axis is a series of values that represent rainfall storm
duarations in minutes, i.e. 10 min, 30 min, etc. The y axis values are
the
intensity of the storm, i.e 1 inch, 3 inches, etc. Somehow, either with
the
chart or data table, I need to interpolate for storm durations that I put
in.
In simpler terms, if I put in say 12 min., (data for 10 and 15 are in the
table), I need to find out what the intensity is by interpolatation. To
further complicate matters, I need this interpolated value to go in a cell
in
different parts of my spreadsheet.

The easiest option may be to use the LINEST function to pull out the slope &
intercept parameters for the line between your two data points, & then use
those to calculate the interpolated value.
--
David Biddulph

See the 'Intercept Vertical Lines' sample at
http://www.edferrero.com/charting.aspx

Ed Ferrero
Microsoft Excel MVP
http://www.edferrero.com