1 These are: random samples. quota samples.

2 The major defence pollsters give is that quota samples generally predict the outcome of elections pretty well.

3 Quota sampling is like stratified sampling, but with an important variation.

4 Quota sampling is widely used in market research as it is cost-effective.

5 Opinion polls in Britain are almost always conducted on quota samples.

6 Among the inheritance of this type of survey are procedures known as the quota sample and the attitude questionnaire.