John would like to conduct a survey in his neighborhood to get homeowners' opinion on Delmarva proposal to switch to natural gas. Which of the following is an example of a stratified sample?
A) John randomly chooses three streets and selects every third house on those streets.
B) John selects the first 25 homes that he passes as he walks into the entrance of the development.
C) John selects every third house on each street.
D) John divides the population into two-story, split-level, and ranch houses. Then, he selects a proportional amount of houses from each group.

Question

Quizplus · Accepted Answer

Stratified sampling involves dividing the population into distinct subgroups, or strata, and then randomly selecting samples from each stratum in proportion to the size of the stratum. In this case, John has identified three different types of houses and will select a proportional amount of houses from each type, which is an example of stratified sampling. The other options do not involve dividing the population into distinct subgroups and selecting samples from each subgroup in proportion to its size. A randomly chosen three streets or the first 25 homes may not be representative of the population, and selecting every third house on each street could result in a biased sample if the houses on each street are not similar.

John Would Like to Conduct a Survey in His Neighborhood