logarithmic trendlines using zero values

[BToddH]

Version: 2008
Operating System: Mac OS X 10.5 (Leopard)

Hi,
I would like to add a logarithmic trendline to my scatter plot. However, when I attempt to do so, i get an error message indicating that some trendline options do not allow zero or negative values. (There is one zero value as the first data point on the x-axis). I have never had this problem with other versions of excel, where zero values were appropriately graphed. The data is clearly best represented using a log scale. Any suggestions?
Thanks.

 

[Mike Middleton]

BToddH -

I have never had this problem with other versions of excel, where zero
values were appropriately graphed. <

It has always been the case for all versions of Excel that the logarithmic
trendline does not allow any zero or negative x values.

One workaround is to add a constant to all x values. Another workaround is
to plot only the positive values.

Another workaround (likely the most appropriate for your situation) is to
have two data series, the first with the zero and negative values (just one
point for your situation), and a second series with the positive values, and
then add the log trendline only to the second series.

- Mike
http://www.MikeMiddleton.com

 

[BToddH]

Thanks for your response. I must have been confused about what I did in the past. I will try your suggestions.