What's the difference between Qualified & Unqualified visitors?

What’s the difference between Qualified & Unqualified visitors?
A Qualified visitor is a person who entered your funnel at the very beginning, via the funnel Entry Page, whereas an Unqualified visitor is someone who entered your funnel somewhere in the middle, skipping the first page of your funnel.
For marketing analysis and optimization purposes, you’ll almost certainly want to look at and use stats based on Qualified Visitors, which is why this is the default setting—but you can change this filter if you want to, for example, to see the difference in results between your Unqualified and Qualified visitors.