jQuery selectors and HTML5 data-* attributes set dynamically

I have this working:

  <div data-people="australian">Australian people eats...</div>

  <script type="text/javascript">
    alert($("[data-people=australian]").html());
  </script>

But this other doesn't work and I don't know how to solve:

  <div id="mich">Australian people eats...</div>

  <script type="text/javascript">
    $("#mich").data("people", "australian");

    alert($("[data-people=australian]").html());
  </script>

Why I can't set the data-* HTML5 attributes from jQuery and the use them to select a DOM object???

Lot of thanks