Final answer:
Selection bias refers to a polling error that occurs when the sampling method causes the sample to be unrepresentative of the population, leading to overrepresentation or underrepresentation of certain opinions.
Step-by-step explanation:
The polling error that arises when the sample is not representative of the population studied and overrepresents or underrepresents some opinions is known as selection bias. This type of bias occurs when the method used to select a sample causes it to be unrepresentative of the population being studied. Common issues leading to selection bias include using non-random sampling methods, response bias, and social desirability bias. To minimize selection bias, it is crucial to employ random sampling techniques and ensure that all members of the population have an equal chance of being selected. Sampling errors such as selection bias can lead to inaccurate conclusions and are often found in contrast to chance errors, which can be reduced by increasing the sample size.