Question

identify the sampling techniques used, and discuss potential sources of bias (if any). explain
in 1965, researchers used random digit dialing to call 1400 people and ask what obstacles kept them from buying insurance
what type of sampling was used?
a. convenience sampling was used, since the 1400 phone numbers that were easiest to reach were selected
b. cluster sampling was used, since the phone numbers were divided into groups, several groups were selected and each number in those groups was called
c. simple random sampling was used, since each number had an equal chance of being dialed, so all samples of 1400 phone numbers had an equal chance of being selected
d. systematic sampling was used, since phone numbers were selected from a list using a fixed interval between phone numbers
what potential sources of bias were present, if any? select all that apply.
a. individuals may have not been available when the researchers were calling. those individuals that were available may have not been representative of the population
b. if there was a regular pattern to the numbers dialed, it is possible for the sample to not have been representative of the population
c. 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.
d. individuals may have refused to participate in the sample. this may have made the sample less representative of the population
e. there were no potential sources of bias

Explanation:

1. For the sampling - type question: In random digit dialing, each phone number has an equal chance of being dialed, which is the characteristic of simple random sampling.
2. For the bias - source question:

• Non - response bias can occur as individuals may not be available or may refuse to participate (options A and D).
• Sampling bias can occur because telephone sampling only includes people with telephones, and those with telephones may not be representative of the whole population (option C). There is no indication of a regular pattern in the dialed numbers to suggest bias in option B.

Answer:

What type of sampling was used?
C. Simple random sampling was used, since each number had an equal chance of being dialed, so all samples of 1400 phone numbers had an equal chance of being selected

What potential sources of bias were present, if any? Select all that apply.
A. Individuals may have not been available when the researchers were calling. Those individuals that were available may have not been representative of the population
C. 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
D. Individuals may have refused to participate in the sample. This may have made the sample less representative of the population