On 21/01/2010 2:43 PM, mlcarte3 wrote: > I have a 3d scatter plot and I need to add a trend line. I can add a > regression plane, but I need a line, not a plane. > Which line do you want? There's more than one choice. For example, you could regress y and z on x, or you could find the principle axis of the x, y, z point cloud. Duncan Murdoch