If it is a
radiobuttonlist
Try something like though I didn't test it should work.
function GetRadioButtonValue()
{
var rad = document.getElementsByName("radid");
for (var j = 0; j < rad.length; j++)
{
if (radio[j].value='Yes'){
document.getElementById('Panelid').style.display = "none";
}
else
{
document.getElementById('Panelid').style.display = "block";
}
}
}