excel graphing tool or vba solution

Question

i have a histogram in Excel. I added a trendline to this histogram which looks like a normal curve.

_{(source: sourceforge.net )}

(it is the image all the way to the left)

I would like to know how I can identify a datapoint on the trendline

Is there a tool that does this? The solution can be in VBA if it needs to be.

Answer 1

If you format the trendline, you can display the equation for the trendline on the chart. You can then copy the equation into a cell and for any value of x you input, you can calculate the y value.

EDIT

I used this VBA code to programatically retrieve the equation from the trendline. Maybe it will help.

Sub ChartStuff()

    Dim cht As Chart
    Set cht = Charts("Chart1")

    Dim ser As Series
    Set ser = cht.SeriesCollection(1)

    Dim tnd As Trendline
    Set tnd = ser.Trendlines(1)

    MsgBox (tnd.DataLabel.Caption)

End Sub

EDIT

To move the chart so that it is its own sheet, not an object on a worksheet, right-click on the chart object, choose the 'Move Chart' option, and select the 'New Sheet' radio button. This will create a new tab in your workbook that is only the chart. You can then refer to it by the name on the tab.

Answer 2

You could take your points put them into a different graph and then extract the trend line equation. You could also use Excel's line estimate function "Linest".

Here's a few resources on it:

http://chandoo.org/wp/2011/01/26/trendlines-and-forecasting-in-excel-part-2/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+PointyHairedDilbert+%28Chandoo.org+-+Learn+Excel+%26+Charting+Online%29

http://newtonexcelbach.wordpress.com/2011/01/19/using-linest-for-non-linear-curve-fitting/

http://newtonexcelbach.wordpress.com/?s=linest

Hope this helps!