Hi Rachel,

If the size legend isn't showing in your view, then go to the show/hide cards button:

And check on the Size Legend. Now go to the little triangle in the corner of the legend:

Select Edit Sizes. Which will give you this dialog box:

Lots of options to play with! Note: The color of the pill on the size shelf makes a big difference (discrete or continuous). Let me know if want to make the range of size even larger there are some tricks for doing this.

--Shawn

If your size slider is already set to max, you may have to draw the circles yourself:

2nd to last post here: http://community.tableau.com/thread/117325

You could still use it - they are only polygons - the equation would be similar.

Rachel,

The 'trick' with size is to get a wide range of sizes in the viz, but only show the ones you want to use. Here's a description of what I did with a map, but I'm pretty sure the same concept will work on a chart.

The interstate signs are the smallest shape, while the Calendar pages & shadows are the largest size shape. To get this spread you'll need to put some dummy data into your spread sheet, something like this:

And then store these dummy shapes in the viz out of view. In the map version I just assigned them all a lat/long that was out of view. In a chart you'll need to assign them values that will place them away from your other data, then fix the axis so they are push out of view. Alternately you could stack them all up on 0,0 with the largest on top. Won't look great, but then your axis can float. After you've got this range variance set, you then assign your real data a size somewhere on the scale (in my case 1-24). Like this:

This is how I got the calendar shapes to be large enough to read, and kept the other icons to a reasonably small shape. I experimented with this a lot, and found that you have to have all the sizes in the viz. If you only put say 1, 2, 3, 4, & 23, you'll only get five sizes equally stepped up in size. So make sure there's at least one shape for every size in the viz.

If you post a packaged workbook I'll set it up for you.

--Shawn

EDIT: I just realized that if you create a custom shape that is a thin white line or circle, you can assign this to the dummy shapes and 'hide' (white on white) them at the 0,0 chart location.