I'd try and find them in your own geographic area/state etc.  Then when you
write it up  you say the sample was from xyz state in the [mid] XYZ states
and may not be applicable to other areas.  To start with 50 from each group
from all over the US/world wouldn't be a decent sample to my mind.  But
research isn't my area, so hopefully someone with more expertise will
reply.  Sincerely, Pat in SNJ

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