No it's not. It's impossible to fit in so small sample every social group, every age group, every profession group, residents of cities and villiges, every region residents, every religion group etc. All that can have influence on people opinion and to be honest everything has. Education, sexual orientation, skin color, everything. And if you want your research to be a reflection of reality, so to say, you must have representatives of all possible groups in it (with equivalent percentage of ich).