What's the best way to make an ellipse (rather than bubble) chart in Excel?
May 15, 2006 4:39 PM   Subscribe

Let's say I want to make a chart that's like an excel bubble chart, but I don't want the size of the bubble to vary depending on a third variable. Instead, I want the width of each bubble to vary by some amount, and the height of each bubble to vary by a different amount.

This would result in ellipses rather than circles/bubbles. And, in fact, for each ellipse, I want the width to represent some x range, and the height to represent some y range.

To clarify, here's an example. Say I want to graph the median diameter (x) vs. median height (y) for different types of trees. A scatter plot would be great for this. But, I want to graph the *range* of heights vs. *range* of diameters for different types of trees. So, for example, oak trees would be represented by an ellipse with a minimum x value equal to the minimum diameter for oaks and a maximum x value equal to the maximum diameter for oaks. Likewise, the ellipse would have a minimum y value equal to the minimum height for oaks, and a maximum y value equal to the maximum height for oaks. Then there'd be an ellipse for maples, an ellipse for pines, etc.. This ends up being somewhat like a series of points with x and y error bars.... But I want ellipses. (Also, as far as I can tell, having a different 'error' for each point isn't so easy.)

The "Floating Bar" chart in excel is sort of like this, but the thickness of the bars doesn't vary -- only the length.

Any suggestions on how to get Excel (mac) to do this? (Or ideas about other software that would?)
posted by sentient to Computers & Internet (2 answers total)
 
When I do this exact thing, I plot each point with custom X and Y error bars, then draw ellipses using the bars as guides. It's sort of "cheating", but I've found it works well. There may be a quicker way to do it though.

...having a different 'error' for each point isn't so easy.

That's the custom option under the error bars menu. Just create four more columns representing the max/min diameter and max/min height and refer to those columns next to the + and - respectively.
posted by nekton at 4:48 PM on May 15, 2006


Response by poster: Thanks nekton -- that definitely helps. I didn't realize that specifying a range of values (i.e., column) in the error fields would work to assign a unique error to each point.
posted by sentient at 5:14 PM on May 15, 2006


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