also, what’s the size limit for the city variable or metro variable? when I crosstab metro area with city, some of the smaller cities don’t show up even though in a small city metro area…
In ACS samples, responents are given a code of “Not identifiable” if the PUMA boundaries within which that respondent lives do not match up with METAREA boundaries. This is briefly discussed in the User Caution note at the bottom of the METAREA Comparability Statement, as well as on the Incompletely Identified Metropolitan Areas page.
See the Answers to this question for more info about CITY.