13.All census questions are tested to establish:
	that respondents understand them;
	that they are publicly acceptable;
	that the quality of the response is sufficiently high for reliable information to be obtained; and
	that they do not have an adverse effect on response rates to the Census as a whole.
An earlier version of the proposed question on religion was included in the Census Rehearsal in April 1999 and satisfied these tests.
Background Technical issues.