/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 1 Liar, liar! Sometimes police use... [FREE SOLUTION] | 91Ó°ÊÓ

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Liar, liar! Sometimes police use a lie detector (also known as a polygraph) to help determine whether a suspect is telling the truth. A lie detector test isn’t foolproof—sometimes it suggests that a person is lying when they’re actually telling the truth (a false positive). Other times, the test says that the suspect is being truthful when the person is actually lying (a false negative). For one brand of polygraph machine, the probability of a false positive is 0.08. (a) Interpret this probability as a long-run relative frequency. (b) Which is a more serious error in this case: a false positive or a false negative? Justify your answer.

Short Answer

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(a) A false positive occurs in 8% of truthful cases. (b) False negative is more serious as it may let a guilty person go free.

Step by step solution

01

Understand the Probability Context

The probability of a false positive is given as 0.08. In the context of long-run relative frequency, this probability means that out of 100 tests where the suspect is truthful, the polygraph will incorrectly indicate lying in 8 of them.
02

Define the Error Types

A false positive occurs when the test indicates a lie, but the person is truthful. A false negative occurs when the test indicates truthfulness, but the person is lying. Understanding these errors helps us evaluate the seriousness of each type.
03

Evaluate the Consequences of a False Positive

A false positive could lead to wrongful suspicion or accusation of an innocent person, potentially resulting in emotional distress, legal consequences, or reputation damage.
04

Evaluate the Consequences of a False Negative

A false negative could allow a guilty person to be wrongly perceived as innocent, potentially leading to failure in delivering justice and preventing a criminal from facing appropriate consequences.
05

Compare Seriousness of Errors

In legal justice and public safety contexts, allowing a guilty person to go unpunished (false negative) is typically considered more serious than wrongfully suspecting an innocent person (false positive). This is because it could potentially result in further harm or crime.

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Key Concepts

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

False Positives and Negatives
When we talk about false positives and negatives, we're diving into the world of errors where a test, like a polygraph, might give incorrect results. Think of a false positive—this happens when a test wrongfully indicates a lie when the person is truthful. It's like being marked absent when you are actually in class. In contrast, a false negative occurs when a test wrongly indicates truthfulness even though the person is lying, similar to mistakenly passing a student who failed. Understanding these errors is crucial in deciding the reliability of tests. False positives can cause undue stress or misjudgment, while false negatives might allow dishonest behavior to go unnoticed. By clearly defining these terms, we pave the way for a deeper grasp of their implications in real-world situations like legal investigations.
Polygraph Test
Polygraph tests, commonly known as lie detector tests, are tools used to infer the truthfulness of someone's statements by measuring physiological responses. These tests monitor changes in factors such as heart rate, blood pressure, and skin conductivity, under the assumption that lying will produce physiological changes. However, polygraphs are not foolproof. Their reliability is often questioned due to the likelihood of false positives and negatives. Hence, they are seen as supportive evidence rather than definitive proof in legal settings. Understanding the limitations of polygraphs is important for interpreting their results accurately and ethically.
  • It helps to pair polygraph attempts with other investigative methods.
  • Being aware that anxiety and nervousness can also contribute to false readings is critical when analyzing test outcomes.
Long-Run Relative Frequency
The concept of long-run relative frequency can be a bit abstract, but it's a powerful tool in probability. It's like predicting outcomes over a long series of trials. When we say the probability of a polygraph giving a false positive is 0.08, we mean that in the long run, 8 out of every 100 tests may incorrectly flag a truthful person as lying. This perspective emphasizes frequency over time, helping us predict how often a specific event will occur. In the context of false positives and negatives, understanding long-run relative frequency assists us in evaluating the reliability of a test. If the long-run relative frequency of false results is low, the test is considered more reliable.
Error Analysis in Statistical Testing
Error analysis in statistical testing is essential in evaluating tests like the polygraph. It involves assessing the likelihood and impact of errors, namely false positives and negatives, to refine testing procedures. By thoroughly understanding these errors, we can mitigate risks and enhance decision-making. For instance, in a legal context, a false negative can result in a criminal escaping justice, potentially endangering society further. Meanwhile, a false positive can cause harm to an innocent person's life. Through error analysis, we investigate how to balance these risks and implement strategies to minimize errors.
  • Increasing awareness about testing limitations is part of effective error analysis.
  • Continuously revising methods based on new data can improve testing accuracy.
By focusing on error analysis, we can develop more robust and fair testing systems, ultimately leading to improved outcomes in various fields.

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