Human populations are heterogeneous. That's a low level, but extremely important fact of life that social scientists have to deal with. Heterogeneity is, of course, a matter of degree and knowing when to treat differences as too trivial to merit attention is something that is mostly learned by experience. Why these abstract musings?
My 20 minute walk into work takes me through two distinct residential areas. The first is the South Oxford academic ghetto that I live in. As I'm walking along this morning I count the number of houses displaying an EU referendum poster. I estimate that 10-15% of houses have a poster taped to a front window and 100% of these posters are for Remain.
Then I cross over the bridge and pass though a rather different area, mostly 1970s social housing. The adults heading in the opposite direction to me, mostly taking their kids to school on the other side of the river, are different in all sorts of respects. When I look at the houses and flats they have come from one thing is immediately obvious: not a single one has a referendum poster in the window.
Two worlds separated by 25 metres of water. One confident enough to express their opinion the other...actually I don't know. Maybe most are not interested. Maybe nobody asked them. Maybe their tenancy agreement doesn't permit the display of posters in the window.