Final answer:
The example of a national survey company picking phone numbers from each area code to poll opinions on political issues is an example of random sampling and probability sampling, which includes equal chance for selection and is typically performed using random digit dialing.
Step-by-step explanation:
An example of random sampling is best demonstrated by the scenario where a national survey company picks one phone number from each area code in America to call and ask for an opinion on current political issues. This method exemplifies probability sampling where researchers choose samples randomly from a larger population, ensuring that each person has an equal chance of being selected. This practice follows the principles of random digit dialing, which is a method that selects people for surveys by generating telephone numbers at random, typically done by a computerized system.
Random sampling allows researchers to generalize the results to represent the larger population's views accurately. It is crucial in obtaining a sample that is free from biases and reflective of the population's demographics, such as in presidential elections or consumer product feedback, where the aim is to gauge the broader public opinion.
Other methods such as stratified, systematic, cluster, or convenience sampling use different selection criteria and may not provide an equally random sample as the one described by the national survey company's method.