Question: Graphing 2 variables dependent on 3rd
 

I want to graph the relationship between two variables (while also noting a third variable (the date/the performance of the stock market) as that has an effect on the first two variables.

What's the best way to do this?

I tried an XY Scatter with a best-fit line graphing the two variables, but that doesn't account for third at all.

Even if it's something as simple as labeling each of the points on the XY Scatter right now with the third variable text (which I would make the date in this case), that would do the trick in a pinch.

The first thing that comes to mind would be superimposing some kind of line or scatter graph with the X and Y variables over a bar graph of the Z variable (tied to the horizontal axis by time increments or the X variable, as the case may be).

Would a bubble chart work to vary the size of the point based on the 3rd variable?

You could also create multiple series for each of the different values of the 3rd variable. You just need to sort your data first.

Maybe use color to represent the third variable? Green = high, red = low, or some sort of color scale.

Thanks for the thoughts guys - I toyed with a couple of them yesterday, and think I got it figured out in a way that looks good.