If you type the word TREND into Excel help, one of the topics is:
Equations for calculating trendlines

Also at
http://office.microsoft.com/en-us/he...01178621033and also see http://office.microsoft.com/en-us/ex...33.aspx--David Biddulph"PA" wrote in ... We are conducting some research on welding and have some X-Y data plotted where the Y axis corresponds to # of Inclusions, and the X axis isthickness. I have done a Scatter Plot, and wish to add a Trend Line. The question is: what is the difference between a Linear and Logarithmic Trend Line. Thanks Paul