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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 Key terms: population : the group you want to know about

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Opinion Polling as a “science”

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Opinion Pollingas a “science”

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

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%


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


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 don’t 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…

“Statistical Magic of Polling”

…“coin flip” example

Exercise: FIND me the latest Obama/Hillary poll results…

…the “soup” analogy


Margin of Error…

…increase in sample size [decrease in Margin of Error] must be balanced with rising $$$ cost of contacting more respondents!!!



  • …increasingly an issue
  • range between 30 and 40% of all attempts
  • again, it becomes a big problem IF there’s 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!


…some credible; MOST are NOT! [pseudopolls]


* 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 =


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



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?