Creating linear regression using partial data

[reinhardn]

I have plotted a set of 30 data points in excel. I need to create a linear regression but only using the first 5 points and not the total 30 points. The entire 30 points must remain on the graph.

Is there an efficient way to do this in Excel 2007 or Excel 2003 (or both)?

Thanks for the help.

[MrShorty]

Considering the kinds of changes MS makes, I doubt it's much different than in 2002.

If you want to use the chart trendline tool to do the regression, you'll need to separate out the 5 desired points into a 2nd data series, plot that data series, then base a trendline on that 2nd data series. If needed, format the 2nd data series so it is effectively invisible.

My preference is to use the LINEST function. Depending on how your data are set up, it would be easy enough to specify to LINEST which portion of the data set to use. If you really want to build the input matrix, it's possible to create an input matrix that will allow you to specify which points to include in the regression using a weighting factor/toggle.