The most important characteristic of a sample that makes it possible to generalize the results of a research study to the population from which the sample was selected is that it is, on average, representative of that population. Which of the following is most likely to ensure the sample is truly representative?
1. The sample is selected at random from the population
2. The entire population is included in the sample i.e. it is really a census
3. The sample is carefully screened to ensure that it contains, proportionately, people with the same demographic profiles as encountered in the population.
4. The sample is selected quickly, even at the risk of its being non-random to ensure that opinions are 'fresh.
5. None of the above are correct
Answer: 1. The sample is selected at random from the population