# [SIGMAPLOT v12] correspondence analysis to gaussian curve

#### John_

##### New Member
A correspondence analysis was performed, which generated an X and a Y coordinate. I have a third value that I want to use as a Z coordinate. How can these three values be used to create a gaussian curve in SigmaPlot?

#### gianmarco

##### TS Contributor
Hi,
in order to provide help, it wuld be useful if you could describe the issue in some more detail, providing some background of you study/analysis as well as your goals.
Provided that I do not understand what would be the purposes of "create a gaussian curve" in the context of Correspondence Analysis, I would like to know what the z coordinate represent.

Regards,
Gm

#### John_

##### New Member
not a problem, thanks for your reply. Looking back, you're right, there isn't much to go on. Here are some details:

The objective is to plot the abundance of harmful algal species in a 3d graph. A CA produced an x and a y coordinate for each species, which was successfully plotted on a 2d graph. The relative position of all of the species on the graph indicates their similarity to one another.

The point on the 2d graph represents the peak abundance of a species. Underneath that point (which isn't shown) is a unimodal mound, representing the distribution of this species. More area = more of the species. I want to create a gaussian curve as the unimodal mound. As for the shape of the mound, I have the number of units (length) of the base of the curve on the y and x axis.

The Z coordinate is another variable (biovolume) that I want to use to compare all of the species. Plotting the CA x, the CA y and the biovolume is no problem, but I want to plot a gaussian curve underneath the xyz point using the curve length data to shape it.

Overall, there are 5 pieces of data per species. An X value from the CA, a Y value from the CA, a Z value (biovolume), length on the Y axis and length on the X axis.

Any thoughts? or would you like anything clarified further?