I have a quiz where people fill out 15+ questions to find out what kind of traveller they are. My client would like to ask them for their postal code, so that they can ultimately send people information and offers that are customized to their traveller type and location. They would also like the postal code to validate the geo segmentation research about the traveller type differences by location.
Quiz respondents are not asked for their full mailing address. They have an option to opt in to receive further information by providing an eMail address.