The graphical analyses are interesting with regards to the statistical analyses. They allow you to see at one glance your results.
Select first a question in the panel on the left hand-side of your screen . If you want, you can also select a segmentation.
Based on the question type, you can have a graphical analysis available or not:

Question type	Statistical analysis
Comment
Open
Single choice
Multiple choice
Drop-down list
Survey
Single-choice table
Multiple-choice table
Uni-row table
Uni-column table
Double-row table
Double-column table