Recently I have had to think about the possible population sizes of individual Pompeian city blocks, and insula IX, 3 in particular. While the question of the total population size of Pompeii remains much debated and the estimates vary greatly, I have not come across many (well, none) estimates of populations in individual city blocks, if not including simplistic divisions of the total assumed population by the number of assumed insulae. And the only discussion I can think of on the possible breakdown of the population into different housing units is Wallace-Hadrill´s article Houses and Households: Sampling Pompeii and Herculaneum (In Rawson (ed.) Marriage, Divorce and Children in Ancient Rome 1991). Working down from a total population of 10 000, he divided houses of Pompeii into four quartiles on the basis of a sample study, and proposed a certain number of individuals in each type of houses.
Following his categorisation a total of some 120 individuals in insula IX, 3 can be suggested. However, if we assume that some houses were uninhabited or their population was reduced in AD 79, we must decrease the number. If we assume that the total population of Pompeii was greater than 10 000, or if we assume that upper floors of the insula housed more people, we must increase the total. The number remains very hypothetical.
Nevertheless I would be curious to hear opinions about the overall topic of population estimates, references to other estimates of populations of insulae and in general thinking about the spilt-up of the total population.