This document shows the differences between a few different types of Set Analysis operators, and specifically why using the *= notation is often better than using a straight = comparison.
When you use *= the users selection is taken into account, making a much more intuitive dashboard.
This example was created to provide an illustration to a blog post that looks into the use of this notation, which can be read here:
The blog post goes into detail about what happens when you use each of the different syntax in your expressions.
There are a number of other tutorials and downloadable examples on our website here:
If you have any questions please post them in the comments below.