C.G.
I have never interviewed a nanny. My kids have always been at a daycare center. I am much more comfortable with a center that is licensed and regulated. You know staff has to go through training/certifications and specific qualifications. The advantage of a center vs nanny is that if the usual caregiver is sick, in a center, there will always be coverage for your child. With a nanny, if she's sick, you have to either stay home or look for alternate care at the last minute.
I just think to all those stories you hear in the news about tragedies in the daycare and 9 times out of 10 it usually is a child getting care in someone's home.
Yeah, daycare centers may be more expensive than a nanny in her home, but for me, I feel it is worth it.
If she comes with great references though, I would go for it. Just make sure she is certified in infant and child CPR (ask to see her CPR card), does she have any qualms about taking your child if your child is sick? Is she planning any vacations in the next several months. Does she plan to give you well enough advanced notice when she does so that you have the time to find alternate care? Also, a very good question (IMO), if your daughter is not vaccinated, are her children vaccinated and if not, will she be attuned to any sicknesses that her children get that might put your daughter at risk? With H1N1 going around, does she plan to disinfect all the surfaces that your daughter will come in contact with. (Think - her children are in school and in an environment where this disease is showing trends in spreading, there is always the possibility of them bringing anything and everything home).