The poll was conducted last Monday and Tuesday among a national quota sample
of 1,000 voters throughout all constituencies.
40) acknowledges that 'a quota sample
will inevitably be biased towards those who are more easily available: someone who hardly ever goes out is far more likely to be in if a quota interviewer calls, than someone who is almost always out.
A stratified quota sample
(N=180) was classified into 18 categories based on age, gender, and socio-economic status level (SES).
Most significantly, the CES survey has been based on a quota sample
since its inception, which predated the introduction of probability sampling as the internationally recognized standard for sample surveys.