Yes, for a search to be considered narrow, the resulting group should be small and specifically defined by precise criteria, not encompassing a significant portion of the population. *Notice once criteria are stacked groups can get small.* E.g. Which young males on your street (or in your building) who like Trump but not Israel were protesting at city hall today? Big datasets let authorities / advertisers / ... answer questions like that. The answer will often be a tiny "narrow" fraction of the population (of your city / state / country / ...).