at the start of each plot, there were a bunch of x values around zero, some
positive, some negative, some zero, but my plot was formatted so that i
didn't see negative values cause they were inconsequential. thanks a lot for
your help, i couldn't figure it out.

"Andy Pope" wrote:

Do you have zero or negative x values?

mpd4 wrote:
I have 22 plots that are all a similar, logarithmic shape, yet only three of
them give me the option to add a logarightmic trendline.

The plots where the logarithmic trendline does work are perhaps closer to a
true logarithmic shape than those where it does not work, but not by much.

Does the logarithmic trendline only work when the shape is very close?

--

Andy Pope, Microsoft MVP - Excel
http://www.andypope.info