Pros and cons of public opinion polls - Jason Robert Jaffe

326,340 views ・ 2013-05-17

TED-Ed


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Transcriber: Andrea McDonough Reviewer: Jessica Ruby
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We are constantly asked for our opinions.
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Which team do you think will win the Super Bowl?
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Who wore it better on the red carpet?
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Who are you going to vote for for mayor?
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Public opinion polls are everywhere.
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Important decision makers in American government
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have long relied on public opinion polls
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throughout elections and important legislation.
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The problem is public opinion isn't easy to track
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and, often times, isn't even right.
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In 1948, the <i>Chicago Daily Tribune</i> ran a now famous headline:
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"Dewey Defeats Truman,"
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they cried in big, bold, black and white letters.
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The problem is
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that Dewey hadn't defeated Truman.
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The <i>Tribune</i> had relied on polls to come to their conclusion.
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Whoops!
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This happens all the time because public opinion polls
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are either inaccurate or misleading.
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So, why are they wrong?
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And why do we keep using them?
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First, let's start with an important term:
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sample.
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A sample is the group of people
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that respond to questions during a public opinion poll.
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A poll's quality rests largely on its sample,
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and a sample can be bad in a few key ways.
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It can be too small,
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too narrow,
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or the poll itself can be too difficult.
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Polls that are too small are bad for obvious reasons.
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And while you can't possibly ask
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every single person in America for their opinion,
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the more people you ask,
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the more accurate your prediction.
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Polls that are too narrow,
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that only ask a certain type of person a question,
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are bad, too.
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Consider a poll about whether or not
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the potato is the best vegetable in America.
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If you only asked people in Idaho,
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where the state food is the potato,
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chances are that you would get a much different answer
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than if you asked people in the state of New Mexico,
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where the state vegetable is beans.
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Getting the right kind of diversity in your sample
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means making sure that your sample has a range
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of ages,
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races,
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genders,
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and geographic regions,
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just to name a few.
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Finally, polls that are too hard can't tell you much either.
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If you're asking people for their opinions on things
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about which they have no prior knowledge,
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the results will be pointless.
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You're better off shaking a Magic 8 ball.
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It's not just the people you're asking
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that can cause bias, though.
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The person doing the asking is part of the problem, too.
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That's called interviewer bias.
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Interviewer bias is all about the effect
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that the person asking the questions
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has on the sample.
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Humans generally don't like confrontation.
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People worry that their answers may make them look bad.
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Therefore, we find that people tend to give
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socially desirable responses,
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not necessarily their honest opinions,
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because they don't want to come across
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as heartless,
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racist,
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or bigoted.
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And the way we word our questions matters too.
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When polls purposely sway the answers one way or the other,
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it's called a push poll
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because it pushes people to answer a certain way.
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"Would you vote for candidate Smith?"
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is a perfectly normal question.
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"Would you vote for candidate Smith
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if you knew that he robs senior citizens?"
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is a push poll.
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So, if polls are open
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to all sorts of manipulation and inaccuracies,
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why are they still so prevalent?
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Despite their flaws, public opinion polls provide us
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with some sense of the thoughts and moods
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of large groups of people.
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They offer politicians the chance to pass legislation
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they think a majority of Americans will support.
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They help fashionistas on TV
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know which star wore the dress better on the red carpet.
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Finally, they make us,
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the people who get polled,
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feel as though our voice has been heard.
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So, next time you get a phone call asking your opinion,
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or if you see a poll online,
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take some time to think about who is asking
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and why they're asking.
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Then, take that poll, and its results,
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with a grain of salt
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or a potato.
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