[jQuery] Simple question about Radio Buttons

[Namlet]

Why does this line of code not work for the radio button?

if ($(this).attr("type") == "radio") alert($(this).checked);

I get 6 alert boxes (I have 6 Radio Buttons) and the alert says
undefined every time.  But half of them should be true and half should
be false.  Am I doing something wrong?

here are two of the radios:

<input name="recvd_loan" type="radio" value="1" /> Yes
<input name="recvd_loan" type="radio" value="0" /> No

Thanks!