What do we call asking for the minimum information required to do the task?

We have all got kind of used to all kinds of things requiring information they have no reasonable need to.

• Eg a forum requiring your phone number, address and occupation.
• A raffle requiring more or less your life-story.
• Almost everything requires you to give your gender, when that has literally nothing to do with the service being offered.

The reason these are asked for is generally pretty obvious -- it is market research. Though I think there is also a aspect of monkey-see monkey-do. Everyone else did it why shouldn't I?

StackExchange (and other things that let you sign-in/up with only a OpenID) are a refreshing change.

Another example, not online, I am part of a organisation that has a requirement for all members to submit a membership form each year when they renew. One of the services our organisation offers is book borrowing. To borrow a book, a book borrowing form must be completed. Now there were two view points on what should be on the borrowing form:

One said, we need the names of the book, the borrow dates, and there name (or organisation is small enough this is a unique identifier), and their address and phone number. Then if we need to track them down because the book is over-due we can track them down and get it back.

The other argument (mine), said that we just need there name, the borrow dates and the book dates -- none of their details. We don't need the details -- they gave those to us when they submitted their membership form. The reasoning behind this is that it would be a better user experience if it was shorter. Thus would be more likely to use the service, and also to actually submit the borrowing form -- instead of just grabbing the book without filling in a form (which has happened alot historically.)

I'm looking for a term to describe this principle in UX design, so I can research it further. The "Minimise information required/obtained from users" principle.

I'm sure there are other side benefits from following the principle, like minimising the amount of privacy concern overhead in tasks (Such as the need for a Clear Desk Policy)