To address your question I would like to highly suggest please have a glance on What's New in QlikView 11 application file. This comes with QlikView 11.
Comparative Analysis is a concept of comparing two dimensions for instance Product A and Product B or Sales Performance or Your Performance vs Your Friends's performance.
To implement this Alternate States and Groupings are used in properties of objects (in General Tab).
As I mentioned earlier I will highly encourage to see What's New in QlikView 11 application file.