Received a call stating they were calling from the CT state dept of health. After informing them I was on the DNC list they informed they had reached my number through a process of Random Digital Dialing. Which is something about how there diaper is set up with the area code and prefix automatically then the dialed proceeds to dial the last 4 digits at random (I guess to avoid any form of discrimination based on income, martial status, or race). After a few more questions I had felt comfortable enough to participate. No indentifying information was asked of me and for some of the questions I refused to answer the interviewer would politely move on to whatever question they had next without any hassle. It's a long twenty minutes but it was informative and overall not as bad as I had thought it was going to be
I used to work for ICF Macro when I lived in VT. They DO NOT get your number from a list. All they do is plug an area code and prefix numbers into the autodialer system. The autodialer then dials the last four numbers randomly. Sometimes there's a hit with a number - in that case congratulations, we would like to ask you to participate in a survey. Sometimes it's a miss. Wasn't the best job to have when I lived there, but it paid the bills.
No postcard was ever sent and even if it were the laws governing health information and rights to privacy are very clear. When the state and federal government can't protect the information they collect from hackers it is a big deal!