The ABC program Nightline once asked whether the United Nations should continue to have its headquarters in the United States. Viewers were invited to call one telephone number to respond “Yes” and another for “No.” There was a charge for calling either number. More than $186,000$ callers responded, and $67\%$ said “No.”

Calling either of these numbers cost money. More than $186,000$ people called, with $67$ percent saying "No."

A simple random sample (SRS) of size n is made up of $n$ people chosen from the population with an equal chance of being the sample that is actually chosen.

The ABC show Nightline held a poll to determine whether the United Nations' headquarters should be in the United States or not. Many spectators have been summoned for this. More than $186,000$ people answered, with $67$ percent denying it. A voluntary sample is one in which all respondents participate in the survey because it is in their best interests. Because of the participants' interest, this form of sample is also known as a self-selected sample. Because the respondents who are passionate about the topic have answered, voluntary response sampling is used in this circumstance. Those who support the United Nations as the headquarters would be less likely to respond to the question.