Re: Anyone good at Stats? What sampling method is this?
From my understanding there's a fine line between the two - it's not truly random, but then you could argue it never is (as you point out.) If someone was really picking your sampling apart then they could say things like you've only sampled people within that city which isn't necessarily representative, you're more likely to sample people who venture outside often rather than sit at home all day, you're only sampling people that are willing to stop and talk - that sort of thing.
However, you could keep this up forever. What you have shown is that you've made a concerted effort to make it as representative as you realistically can (without knocking on doors or travelling huge distances) and for your purposes that's probably good enough (though you don't say what the purpose is?) As long as you identify the weaknesses in your approach such as I've outlined above, to show you're aware of those weaknesses, I'd say you can make the claim it's pretty representative.
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