Radio Button with Yes/No option and nothing as the default

Hello,

I have a radio button that has two options:  Yes or No.  But neither is the default value.  The Default value is blank.  I'm finding (I think) that whether the default value is blank, it's still sets the default value as "yes".  This is my variable in the presaveaction().

var cip01 = $(":input[name='CIP_x0020__x002d__x0020_Verify_x_d51c08d3-6c01-411d-b0f9-cb0942f33fbf_$RadioButtonChoiceField']").val();
 alert("cip01: " + cip01);

If I leave the as the default (don't select yes or no), the alert still displays "yes".

Am I doing something wrong or is this the case?

Thanks.

Thanks! Patti N.