Opinion Polling as a science

1
Opinion Polling as a science

• - sampling methods
• cell phone/caller ID impact
• statistical magic of polls
• margin of error
• response rates?
• Internet polling
• industry reporting standard

2
Key terms population the group you want to
know about sample the subset of the population
surveyed estimate your predicted for any
question EX Obama has 55 support in
Indiana margin of error /- __ a range
around the estimate, usually at confidence level
of 95... EX Obama at 55 /- 3, so we are
95 sure Obama is betw. 52 58

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SAMPLING methods SRS random (every person in
population has an equal chance of
inclusion/selection) Stratified divide into
characteristics subsets (ex race), then
sample within each Cluster often multistage,
based on sampling geographic areas county,
city, blocks Our Simpson Survey a
list-based survey, closer in some ways to
the U.S. census
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Impact of Cell Phones / Caller ID

• increasingly an issue
• Cell phone only use associated w/ youth
• Caller ID allows more screening of calls
• To the extent youth dont vote in high s and
  the target of many surveys is voting, it
  alleviates the problem (sadly)
• EITHER one of them is a problem IF there are
  systematic differences between the people who
  participate and those who do not answer

5
Statistical Magic of Polling
coin flip example Exercise FIND me the
latest Obama/Hillary poll results the soup
analogy
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Margin of Error
increase in sample size decrease in Margin of
Error must be balanced with rising cost of
contacting more respondents!!!
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RESPONSE RATES

• increasingly an issue
• range between 30 and 40 of all attempts
• again, it becomes a big problem IF theres a
  systematic difference between Y and N
• - pollsters make multiple attempts to hit
  (re-contact) s to raise the response rate
• - problem is BIG for instant response poll for
  example, overnight polls the day after the
  presidential debates!

8
INTERNET / ONLINE POLLS
some credible MOST are NOT! pseudopolls CRED
IBLE use of a pre-recruited panel carefully
selected to represent the population of
interest Harris Interactive, OR the full U.S.
population Knowledge Networks Example
http//news.yahoo.com/polls
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INDUSTRY Reporting Standards
NCPP standards You MUST report (1)
sponsor of poll (2) dates of interviews (3)
interview/contact method (4) population of
interest (5) the N (sample size) (6) margin
of error (/- __, 95 conf.) (7) LINK to full
questions to see wording
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ONLINE EXERCISE Scavenger hunt FIND 3 ex. of
news media-reported poll results, and then APPLY
the 7 reporting rules GRADE their disclosure
from an A to an F how well do they inform
citizens about the methods?

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QUESTIONS ?