Questions and Answers
How was the sample taken, and what was the result of the survey?
The poll was a telephone poll and 90% of the sample said sending a text message while driving should be illegal.
It is possible that if all American adults were surveyed, only 50% would agree with the poll result of 90%.
True
About how many people in the sample supported sending more troops to Afghanistan?
About 526 people
What are the possible samples of size two from a population of two men and two women?
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What would the likelihood be of choosing any one of these samples of size two?
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What is the chance of selecting a simple random sample of size two from this population that is representative?
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What is your population if you want to choose a simple random sample of 20 Friends from 113 on Facebook?
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Which one of the following is not one of the first three reasons listed in the article about why you should be cautious about online reviews?
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What was VIP doing to boost the ratings of its Kindle Fire cover?
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Study Notes
Polling and Public Opinion
- A New York Times/CBS News poll indicates 90% of 1,042 adults support making text messaging while driving illegal.
- Telephone poll conducted from September 19-23, margin of error is ±3%.
- Public opinion on sending more troops to Afghanistan shows 51% support and 43% oppose, with skepticism about Afghanistan as a reliable partner.
Sampling Considerations
- Polling results represent a sample, not all American adults; the sample's agreement does not guarantee the same percentage from the entire population.
- A simple random sample can occasionally represent a larger population well, as illustrated by demographic examples.
Probability in Sampling
- In a four-person population (two men and two women), there are six possible distinct samples of size two, demonstrating the diversity of outcomes in sampling.
- For any distinct sample of size two from a given population, the probability of selecting a specific sample is 1 in 6.
Representativeness of Samples
- To be considered representative, a sample must consist of one man and one woman along with one Democrat and one Republican.
- The probability of selecting such a "representative" sample is not straightforward and is not merely 1 in 2 or 1 in 6.
Population Definition
- When selecting a sample from Facebook friends, the population refers to the entirety of users (all 113 Friends), not just the selected 20.
Online Reviews and Bias
- The VIP brand Kindle Fire cover received 4,945 reviews with an average rating of 4.9 stars, but online reviews can be biased.
- Caution is advised when trusting online reviews due to factors like voluntary response bias.
- An article highlights reasons not to trust online reviews, including the possibility of fraudulent positive reviews, particularly related to socially detrimental products.
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Description
Test your knowledge on statistical concepts from STA 210 Chapter 4 through these flashcards. This chapter covers sampling methods and the interpretation of poll results, including public sentiments on issues like texting while driving. Prepare for your assignments and enhance your understanding of data analysis.
