University I rejected is asking which other one I chose over them; should I tell?

I can't think of any harm in telling them, and in the medium term, this isn't a secret, because it will certainly be clear by the fall where you've gone since your name will probably be put on the department website. If you're uncomfortable, it's certainly fine to wait a bit until you've finalized things at the school you accepted; you don't even need to tell them you're doing that---just wait a bit before replying to the request.

It may help to know that it's standard for schools to want to know where students who reject them are going, so there's nothing unusual or suspicion raising about the question. It's useful information because it helps them assess their program and admissions practices.

There is no harm in letting them know. Universities and departments like to know their competition - if Univ B find out that many of their students are choosing Univ A over them, they can think of ways to better compete with them next year.

I work in a university's market research department. We send out surveys to people who decline an offer, with the aim of understanding:

• Who the university's closest competitors are
• Why applicants declined an offer
• How we can improve

The surveys are anonymised and there are no negative consequences from filling in the survey. Results are presented in the aggregate, i.e. charts of all anonymised respondents are presented in a document to senior managers.

Disclosing this information is optional, has no negative consequences and is a benefit to the university you declined.