Aradio talk show host asked listeners to respond either yes or no to the question, "is the candidate who spends the most on a campaign the most likely to win? " fifteen people called in and nine said yes. what is the implied population?

a. all callers
b. all adults
c. all radio listeners
d. all listeners of the radio talk show

what is the variable?
a. number of callers
b. opinion of a caller
c. number of listeners
d. opinion of a listener

can you detect any bias in the selection of the sample?
a. yes, nonresponse. many listeners may not call in.
b. no, there is no bias in the selection of this sample.
c. yes, there is a systematic bias against those that are not listening to the talk show.
d. yes, voluntary response. those with the strongest opinions are most likely to call in.