Question

in 1965, researchers used random digit dialing to call 1100 people and ask what obstacles kept them from attending town hall meetings. what type of sampling was used? a. convenience sampling was used, since the 1100 phone numbers that were easiest to reach were selected. b. systematic sampling was used, since phone numbers were selected from a list using a fixed interval between phone numbers. c. simple random sampling was used, since each number had an equal chance of being dialed, so all samples of 1100 phone numbers had an equal chance of being selected. d. cluster sampling was used, since the phone numbers were divided into groups, several groups were selected, and each number in those groups was called. what potential sources of bias were present, if any? select all that apply. a. if there was a regular pattern to the numbers dialed, it is possible for the sample to not have been representative of the population. b. individuals may have refused to participate in the sample. this may have made the sample less representative of the population. c. individuals may have not been available when the researchers were calling. those individuals that were available may have not been representative of the population. d. telephone sampling only includes people who had telephones. people who owned telephones may have been older or wealthier on average, and may not have been representative of the entire population. e. there were no potential sources of bias

Explanation:

1. For the first question, in simple - random sampling, every element in the population has an equal chance of being selected. Here, each phone number had an equal chance of being dialed when using random digit dialing, so simple random sampling was used.
2. For the second question:

• Option A: Since it's random digit dialing, there is no regular pattern assumed, so this is not a bias source here.
• Option B: Non - response bias can occur when individuals refuse to participate, making the sample less representative.
• Option C: Availability bias can occur if only available individuals are part of the sample, and they may not be representative.
• Option D: Telephone sampling only includes those with telephones, which can introduce a bias as it may not represent the entire population.

Answer:

1. C. Simple random sampling was used, since each number had an equal chance of being dialed, so all samples of 1100 phone numbers had an equal chance of being selected
2. B. Individuals may have refused to participate in the sample. This may have made the sample less representative of the population.

C. Individuals may have not been available when the researchers were calling. Those individuals that were available may have not been representative of the population.
D. Telephone sampling only includes people who had telephones. People who owned telephones may have been older or wealthier on average, and may not have been representative of the entire population.