Special log-log plot

Welcome to the forum.

Post a workbook.

Making a log-log plot should be easy.

If your spreadsheet contains y and x, you can simply plot y vs x on a scatter plot (2007, 2010 should be similar http://office.microsoft.com/en-us/ex...478.aspx?CTT=1), Then format the axes to be logarithmic (http://office.microsoft.com/en-us/ex...255.aspx?CTT=1).

The tricky part that I see is understanding exactly what you mean by "a linear trendline placed on the log-log plot". On a log axis, x can never be 0, so there is no such thing as a "y intercept", so the equation y=mx+b may not have any real meaning. Perhaps you mean an equation that would appear linear on a log-log plot, which would be something more like ln(y)=m*ln(x)+b -- though Excel's chart trendline feature is not going to call that a "linear trendline".

I tend to prefer to do the regression in the spreadsheet using the LINEST() function. If you are interested, let us know and we can help you perform the regression directly in the spreadsheet without needing the chart trendline feature.