Received both an email and a phone call. Very surprised with the quick decision since my application was not submitted early. Happy with my first offer though!

Submitted my application at the end of October. I also received both an email and phone call.

2.5 years of research and 1 publication

Email offered admission by the department, but was "pending approval" by the Graduate College. Website still says "awaiting decision."

I was accepted previously and allowed to reinstate my application.

I have been in contact with a professor and will actually be visiting the campus later this week so I guess they wanted to get my acceptance in before I visited. This is one of my top choices!

I can say for sure this was unexpected.

Financed by a full scholarship from the UK government, and had obtained approval from my desired research supervisor prior to applying. Submitted application on May 10 -- GAO on May 20 -- conditional offer today.