How many zombies do you know?

Zombification is a serious public-health and public-safety concern (Romero, 1968, 1978) but is difficult to study using traditional survey methods. Zombies are believed to have very low rates of telephone usage and in any case may be reluctant to identify themselves as such to a researcher. Face-to-face surveying involves too much risk to the interviewers, and internet surveys, although they originally were believed to have much promise, have recently had to be abandoned in this area because of the potential for zombie infection via computer virus.