Code:
//How do I make the $ignore available to .validate

$(document).ready(function() {

	var $ignore = "";

	$("#sb").change(function() {
	
		var $sb = $('#sb').val();
	
		if ($sb == "section1"){
			$ignore = ".s1";
		}
	});

	$("#test").validate({
		ignore: $ignore //how do I pass $ignore here
	});
});