When you come across a set of labeled radio buttons how does a user know the purpose of these controls?
There is a way to logically and visually group form controls (radio buttons, check boxes, etc.)
Notice the visual grouping. Announces end of grouping.
NO visual grouping, but could be created with CSS. This method would be useful for long legends! No announcement of end grouping, though that could be done via aria.
Digging Deeper - Grouping controls — WAI-ARIA & Non-Standard Form Controls
<form action="">
<fieldset>
<legend>Empty my bank account:</legend>
<input name="radio1" type="radio" value="yes" id="radiobutton1" />
<label for="radiobutton1">Yes</label>
<br />
<input name="radio1" type="radio" value="no" id="radio1" />
<label for="radio1">No</label>
</fieldset>
</form>
...
<p id="faux-legend">Empty my bank account:</p>
<div role="group">
<input name="rb" type="radio" value="yes" id="r1" aria-labelledby="faux-legend yes-label"/>
<label for="r1" id="yes-label">Yes</label>
<br />
<input name="rb" type="radio" value="no" id="r2" aria-labelledby="faux-legend no-label"/>
<label for="r2" id="no-label">No</label>
</div>