Surviving census declarations show that individuals were recorded on a household by household (kat’ oikian in Greek) basis — a single census declaration related to all members of a given household. Luke uses the verb [ἀπογράφω] for the census and, in another place, the noun [ἀπογραφή]. [ἀπογράφω] does not mean “to count” however, but “to write down.” The census involved far more than simply counting the population: large quantities of personal data spanning a consideration range of categories were written down. The Roman Egyptian census declarations contain correspondingly detailed data on parameters including age, sex, occupation, place of residence, familial relationships, number of children, possessions [cf. Census return of five brothers residing together in the city of Arsinoe: SB 10. 10759 dated 35 CE]. Census declarations were archived by officials, compiled into lists by the administrators . . . and used in the computation of taxes. We currently have information on about 400 households in Roman Egypt and on the approximately 1,500 people who lived in those households, and, as excavations in Egypt proceed, new declarations are still being found, edited, and published every year.

Sabine R. Huebner, Papyri ad the Social World of the New Testament, 37.