The classic application of confidence intervals is political polling: the science of sampling relatively few people to predict the opinions of a large population. However, in the 2010s, the art of political polling — constructing representative samples from a large population — has become more and more difficult.
FiveThirtyEight.com wrote a recent article, Is The Polling Industry in Statis or in Crisis?, about the nuts and bolts of conducting a survey that should provide valuable background information for anyone teaching a course in statistics. From the opening paragraphs:
There is no shortage of reasons to worry about the state of the polling industry. Response rates to political polls are dismal. Even polls that make every effort to contact a representative sample of voters now get no more than 10 percent to complete their surveys — down from about 35 percent in the 1990s.
And there are fewer high-quality polls than there used to be. The cost to commission one can run well into five figures, and it has increased as response rates have declined.1 Under budgetary pressure, many news organizations have understandably preferred to trim their polling budgets rather than lay off newsroom staff.
Cheaper polling alternatives exist, but they come with plenty of problems. “Robopolls,” which use automated scripts rather than live interviewers, often get response rates in the low to mid-single digits. Most are also prohibited by law from calling cell phones, which means huge numbers of people are excluded from their surveys.
How can a poll come close to the outcome when so few people respond to it?
Mean Green Math 
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