Final answer:
The sampling method used in the Ohio public opinion poll is a stratified sample, where a simple random sample of registered voters is chosen from each county to collect data on their approval of a smoking ban measure.
Step-by-step explanation:
The sampling method used in the public opinion poll in Ohio to determine whether registered voters approve of a measure to ban smoking in all public areas is called a stratified sample. This approach involves dividing the population into separate groups, known as strata, and then selecting a simple random sample from each stratum. In this case, the strata are the different counties in Ohio and from each county, a simple random sample of 50 registered voters is taken.
Different types of sampling methods yield different levels of accuracy and representation of the targeted population. In probability sampling, each member of the population has an equal chance of being selected, which helps in providing a representative sample. This is essential for creating a reliable snapshot of public opinion. For example, random digit dialing is a common probability sampling technique used in opinion polling.