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Mistaken poll A local TV station conducted a "PulsePoll" about the upcoming mayoral election. Evening news viewers were invited to text in their votes, with the results to be announced on the late-night news. Based on the texts, the station predicted that Amabo would win the election with \(52 \%\) of the vote. They were wrong: Amabo lost, getting only \(46 \%\) of the vote. Do you think the station's faulty prediction is more likely to be a result of bias or sampling error? Explain.

Short Answer

Expert verified
The station's faulty prediction is more likely to be a result of bias. This could be due to the fact that the viewers of that particular TV station and participants in the poll might not be an accurate representative of the entire voting population. The method of collecting responses via text might have also introduced some bias, as it may disproportionately represent certain demographic groups, like younger, more technologically savvy individuals.

Step by step solution

01

Understand Bias and Sampling Error

Bias is an error that results from a systematic difference between the sample and population. In this case, the sample could be biased if the individuals who responded to the text poll were not representative of all voters in the local mayoral election. Sampling error, on the other hand, occurs when a subset of the population is not representative of the entire population because of chance variation.
02

Analyze the Poll Method

The poll was conducted by having evening news viewers text in their votes. This is an opportunity where bias might be introduced, as it suggests that the sample was not randomly selected. It might disproportionately include individuals who watch the news, and possibly individuals who are more technologically savvy enough to text in their votes.
03

Compare Prediction and Result

The predicted result was a win for Amabo with 52% of the vote. In reality, Amabo lost with 46% of the vote. The discrepancy between the two percentages suggests a possible systematic error in how the sample was collected.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Understanding Bias
Bias in survey or poll contexts refers to the systematic error that occurs when certain elements of a population are systematically favored or ignored. This leads to results that do not accurately reflect the entire population. In the case of the faulty mayoral election prediction, viewers of a particular news program were the ones participating in the poll. Therefore, the sample might have represented a segment of the population with specific characteristics, such as political affinity or availability during the news broadcast, rather than the voting population at large.

For example, if the news program is more popular among supporters of one candidate, the poll results would skew in favor of that candidate. This illustrates how understanding bias is crucial for interpreting the validity of poll findings and ensuring that all segments of a target population are given an equal chance to participate.
Sampling Error
Sampling error occurs by virtue of the fact that a sample, no matter how well-chosen, never captures the full nuances of a population. It results from random variations and is inherent in the process of selecting a subset from a larger group. While methodology can minimize it, some level of sampling error is always present in polls.When comparing the predicted outcome and the actual election result in our exercise, it seems likely that the discrepancy could be attributed to more than just random chance. This implies that the error in the poll is more than just sampling error; it may be indicative of bias. That being said, sampling error could still have played a role, especially if the number of respondents to the poll was small.
Representativeness of Samples
The representativeness of a sample is key to the accuracy of survey or poll predictions. A representative sample closely mirrors the characteristics of the population it's drawn from, leading to more accurate results. In the case of the mistaken poll, the sampling method (a text-in vote) was likely non-representative. It probably excluded certain groups, such as non-tech-savvy individuals or those who prefer not to engage with evening news programs.

To ensure representativeness, the sample should have been drawn using a method that does not inherently favor or exclude any part of the population. For instance, including voters from different age groups, socioeconomic backgrounds, and varying degrees of technological access would yield a sample more reflective of the voter population.
Probability Sampling Methods
Probability sampling methods are designed to give all members of a population a known and non-zero chance of being selected. This is in direct contrast to the sampling method used in the poll in our exercise, which was non-probability in nature. Methods like simple random sampling, systematic sampling, stratified random sampling, and cluster sampling are all probability-based and help in creating samples that are free from selection bias and are thus representative of the population.

When using probability sampling, every individual in the population has an equal chance to be included in the sample. Pollsters who employ such methods are better equipped to predict outcomes because they minimize the risk of bias influencing the sample selection process, hence potentially avoiding the type of erroneous prediction made by the TV station.

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