How would I attach or assign values to a trendline?

[williamk2v]

As an appraiser I use Excel to analyze market data and to find the
value of amenities in a given market.

When analyzing market data, I use selling date(X) vs SqFt(Y) to create
a chart. I then create a trendline to present what are sometimes 200-
300 data points into a representation that can be easily understood by
a reader. I usually use a 3-4 order polynomial trendline. In the name
of clarity I can and sometimes do render the data points invisible,
leaving just the trendline.

My question is this: How do I at this point insert along the trend line
values for Y wherever the trendline crosses a point on X?

This would be helpful for figuring the "average value" for Y on any
given date.

Bill McKnight, Appraisal Ace, Citrus Heights, CA

 

[ryguy7272]

Most of what you need to know about excel charts is covered here:
http://peltiertech.com/Excel/Charts/ComboCharts.html

This site is very good too:
http://www.andypope.info/charts.htm

Regards,
Ryan---

 

[williamk2v]

Useful information but the answer to my question is not on either site.

 

[Dave Curtis]

Hi,

You need to have an additional series, "solving" the equation of the
trendline, so you have a y value for each x value.
Then you make a filtered series do determine the values common to the other
two, and just add this filtered series to the chart.
Just the points common to both will appear, ie, effectively where the
trendline intersects with the data line.

Dave

url:http://www.ureader.com/msg/104235902.aspx

 

[williamk2v]

Thanks, Dave. Now that I know it can be done, I just have to figure out the
how to. You are a little over my head with the explaination.