The credibility of the polling organization goes to the heart of interpreting the accuracy of the results. The sample should represent the population being queried. Consider the impact of varying demographics, limiting questions to only those people with listed phone numbers and making contact during limited hours of the day. These factors could impact the outcome. If a telephone survey is conducted and only those folks with listed numbers are called the poll is not random.
Random samples are random in that every person in a group has an equal chance of selection.
The results of random samples can be applied to a larger group because every person in the study group had an equal opportunity to be selected. The results cannot be generalized beyond those who choose to answer. Open-ended questions open the door to bias in interpretation. Multiple coders are needed to decrease the opportunities for bias and should be reported in the report s methodology section. Sometimes organizations will combine the answers from questions to be able to report a more favorable result.