Which sampling method uses a systematic approach to select a representative sub-population without introducing bias?

Which sampling method uses a systematic approach to select a representative sub-population without introducing bias?

• A. It uses a systematic method to select a representative sub-population without introducing bias.
• B. It relies on convenience sampling.
• C. It uses snowball sampling.
• D. It selects participants by voluntary response.

Answer: (A)

Systematic sampling uses a fixed, regular interval to select participants from a complete list, starting from a randomly chosen point. This approach aims to cover the population evenly and reduce researcher bias, because selections follow a consistent rule rather than relying on who is easiest to reach. In practice, you define the population and a sampling frame, decide how many participants you want (n), compute the interval k by dividing the total population size by n, pick a random starting point between 1 and k, and then select every kth person from the list. This method tends to produce a representative sub-sample if the list isn’t organized in a way that aligns with the interval. It avoids the biases of convenience, snowball, and voluntary-response sampling, which rely on who’s readily available, who people know, or who volunteers.

Systematic sampling uses a fixed, regular interval to select participants from a complete list, starting from a randomly chosen point. This approach aims to cover the population evenly and reduce researcher bias, because selections follow a consistent rule rather than relying on who is easiest to reach. In practice, you define the population and a sampling frame, decide how many participants you want (n), compute the interval k by dividing the total population size by n, pick a random starting point between 1 and k, and then select every kth person from the list. This method tends to produce a representative sub-sample if the list isn’t organized in a way that aligns with the interval. It avoids the biases of convenience, snowball, and voluntary-response sampling, which rely on who’s readily available, who people know, or who volunteers.