1. Intro to Stats and Collecting Data
Intro to Stats
2:08 minutesProblem 1.1.30
Textbook Question
In Exercises 29–36, identify what is wrong.
Healthy Water In a USA Today online poll, 951 Internet users chose to respond, and 57% of them said that they prefer drinking bottled water instead of tap water.
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Identify the type of sampling method used in the poll. In this case, the poll was conducted online, and participants chose to respond voluntarily.
Understand the concept of voluntary response sampling. This method often leads to biased results because it tends to attract individuals who have strong opinions, which may not represent the general population.
Consider the potential for selection bias. Since the poll was conducted online, it only includes responses from Internet users, excluding those without Internet access or those who did not see the poll.
Evaluate the sample size and its representativeness. Although 951 responses might seem substantial, the sample is not randomly selected, which affects its ability to accurately reflect the preferences of the broader population.
Reflect on the implications of the findings. The 57% figure may not be reliable for making generalizations about the entire population's preference for bottled water over tap water due to the non-random sampling method used.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Sampling Bias
Sampling bias occurs when the sample is not representative of the population. In this case, the poll was conducted online, and only those who chose to respond were included, which may not reflect the views of the general population. This self-selection can lead to biased results, as it might over-represent individuals with strong opinions about bottled water.
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Sampling Distribution of Sample Proportion
Voluntary Response Sample
A voluntary response sample is a type of non-probability sampling where participants self-select into the survey. This method often leads to biased outcomes because individuals with strong opinions are more likely to participate. In the given poll, the 951 Internet users who responded may not accurately represent the broader population's preferences regarding bottled water.
Recommended video:
05:11Sampling Distribution of Sample Proportion
Generalizability
Generalizability refers to the extent to which findings from a sample can be applied to the larger population. Due to the non-random nature of the sample in the poll, the results cannot be reliably generalized to all people. The lack of random sampling and potential biases mean that the 57% figure may not accurately reflect the true preference of the entire population.
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