The first is to place the script tags where you build and render the visualization inside the div
tags, something like this:
<div> <script> ... vis.render(); </script> </div>
The other way, an this always work is to specify where it will be shown, something like this:
<script> ... var vis = new pv.Panel() .canvas($("vocabulary_chart")) .... </script>
So It will be shown inside the div you specified.
Hope this helps you.