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Water samples are taken from water used for cooling as it is being discharged from a power plant into a river. It has been determined that as long as the mean temperature of the discharged water is at most \(150^{\circ} \mathrm{F}\), there will be no negative effects on the river's ecosystem. To investigate whether the plant is in compliance with regulations that prohibit a mean discharge water temperature above \(150^{\circ} \mathrm{F}\), researchers will take 50 water samples at randomly selected times and record the temperature of each sample. The resulting data will be used to test the hypotheses \(H_{0}: \mu=150^{\circ} \mathrm{F}\) versus \(H_{a}: \mu>150^{\circ} \mathrm{F}\). In the context of this example, describe Type I and Type II errors. Which type of error would you consider more serious? Explain.

Short Answer

Expert verified
Type I error in this case would be concluding that the power plant is not in compliance when in fact it is. A Type II error would be deeming the power plant to be in compliance when it actually isn't. Given the potential environmental implications, the more serious error would possibly be committing a Type II error.

Step by step solution

01

Understanding Type I Error

Type I Error occurs when we reject a true null hypothesis. In this case, it means that we would conclude the power plant to be violating the regulations (mean temperature is over \(150^{\circ} \mathrm{F} \)), when in reality, it is in compliance (the true mean temperature is \(150^{\circ} \mathrm{F} \) or less).
02

Understanding Type II Error

Type II Error, on the other hand, occurs when we fail to reject a false null hypothesis. For this case, this would mean that we determine the plant is in compliance with the regulations, assuming the mean temperature to be \(150^{\circ} \mathrm{F} \) or less, when in reality, the plant is not in compliance, having a true mean temperature above \(150^{\circ} \mathrm{F} \).
03

Deciding which error is more serious

Deciding which error is more serious can be subjective and often depends on the context. However, considering the environmental protection standpoint in this case, a Type II error might be more serious. This is because letting a non-compliant plant continue to operate unimpeded could have serious negative impacts on the river's ecosystem.

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Key Concepts

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

Type I Error
A Type I Error happens when you mistakenly conclude that something is true when it actually isn't. In hypothesis testing, it's like sounding a false alarm. In our example with the power plant, a Type I Error would mean you think the plant is breaking the temperature rule when it's not. It occurs when we reject the null hypothesis (\(H_0: \mu = 150^{\circ} \mathrm{F}\)) even though it's true. This mistake could lead to unnecessary actions like penalizing the power company or imposing stricter regulations when they're actually following the rules.

To avoid Type I Errors, scientists use a significance level, often set at 5% (\(\alpha = 0.05\)). This means there's a 5% risk of concluding a rule violation incorrectly. While avoiding unnecessary penalties is important, it's crucial to balance this risk against the consequences of missing a real issue.
Type II Error
Type II Error occurs when you fail to recognize that something is wrong when it actually is. In our water temperature scenario, a Type II Error would mean assuming the power plant is complying with the temperature regulation when it isn't. This happens when we do not reject the null hypothesis (\(H_0: \mu = 150^{\circ} \mathrm{F}\)), despite it being false.

Such an error is problematic because it underestimates the potential risk to the river ecosystem. Allowing hotter water to continue flowing unnoticed could harm aquatic life and disrupt the environment's balance.

To reduce Type II Errors, increasing the sample size or adjusting the testing criteria can help. Ensuring accuracy in identifying actual rule violations helps mitigate environmental harm.
Environmental Statistics
Environmental statistics involves gathering and analyzing data to understand and protect ecological systems. This discipline provides insights for evaluating natural resources, tracking pollution, and ensuring compliance with environmental laws. In the case of the power plant, researchers use statistics to monitor water temperatures.

Data collection techniques, like random sampling in this scenario, help ensure the analysis reflects true environmental conditions. By observing 50 water samples over time, scientists attempt to determine if the plant maintains proper discharge temperatures.

Statistical analysis in environmental studies enables policymakers and companies to make informed decisions, ensuring public health and ecosystem integrity. It helps in identifying trends, potential risks, and compliance with regulations efficiently.
Water Quality Regulations
Water Quality Regulations are laws and guidelines designed to protect water resources and ensure their safe use. They set limits on pollutants and temperature changes, aiming to minimize human and ecological impact.

For the power plant, compliance means keeping discharged water at or below a certain temperature. These regulations prevent thermal pollution, which can raise water temperatures significantly. This rise can disturb aquatic ecosystems, as species accustomed to cooler conditions might suffer or migrate.

Water quality rules are critical for maintaining biodiversity and sustainability. They enforce standards to prevent harmful practices that could degrade valuable water sources, ensuring they remain viable for future use by both nature and humans.

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Most popular questions from this chapter

The desired percentage of silicon dioxide in a certain type of cement is \(5.0 \%\). A random sample of \(n=36\) specimens gave a sample average percentage of \(\bar{x}=5.21\). Let \(\mu\) be the true average percentage of silicon dioxide in this type of cement, and suppose that \(\sigma\) is known to be 0.38. Test \(H_{0}: \mu=5\) versus \(H_{a}: \mu \neq 5\) using a significance level of .01.

For the following pairs, indicate which do not comply with the rules for setting up hypotheses, and explain why: a. \(H_{0}: \mu=15, H_{a}: \mu=15\) b. \(H_{0}: \pi=.4, H_{a}: \pi>.6\) c. \(H_{0}: \mu=123, H_{a}: \mu<123\) d. \(H_{0}: \mu=123, H_{a}: \mu=125\) e. \(H_{0}: p=.1, H_{a}: p \neq .1\)

The state of Georgia's HOPE scholarship program guarantees fully paid tuition to Georgia public universities for Georgia high school seniors who have a B average in academic requirements as long as they maintain a B average in college. Of 137 randomly selected students enrolling in the Ivan Allen College at the Georgia Institute of Technology (social science and humanities majors) in 1996 who had a B average going into college, \(53.2 \%\) had a GPA below \(3.0\) at the end of their first year ("Who Loses HOPE? Attrition from Georgia's College Scholarship Program," Southern Economic Journal [1999]: \(379-390\) ). Do these data provide convincing evidence that a majority of students at Ivan Allen College who enroll with a HOPE scholarship lose their scholarship?

Typically, only very brave students are willing to speak out in a college classroom. Student participation may be especially difficult if the individual is from a different culture or country. The article "An Assessment of Class Participation by International Graduate Students" (Journal of College Student Development [1995]: 132- 140) considered a numerical "speaking-up" scale, with possible values from 3 to 15 (a low value means that a student rarely speaks). For a random sample of 64 males from Asian countries where English is not the official language, the sample mean and sample standard deviation were \(8.75\) and \(2.57\), respectively. Suppose that the mean for the population of all males having English as their native language is \(10.0\) (suggested by data in the article). Does it appear that the population mean for males from non-English-speaking Asian countries is smaller than \(10.0 ?\)

Let \(\mu\) denote the true average lifetime for a certain type of pen under controlled laboratory conditions. A test of \(H_{0}: \mu=10\) versus \(H_{a}: \mu<10\) will be based on a sample of size 36. Suppose that \(\sigma\) is known to be \(0.6\), from which \(\sigma_{\bar{x}}=0.1\). The appropriate test statistic is then $$ z=\frac{\bar{x}-10}{0.1} $$ a. What is \(\alpha\) for the test procedure that rejects \(H_{0}\) if \(z \leq\) \(-1.28 ?\) b. If the test procedure of Part (a) is used, calculate \(\beta\) when \(\mu=9.8\), and interpret this error probability. c. Without doing any calculation, explain how \(\beta\) when \(\mu=9.5\) compares to \(\beta\) when \(\mu=9.8\). Then check your assertion by computing \(\beta\) when \(\mu=9.5\). d. What is the power of the test when \(\mu=9.8\) ? when \(\mu=9.5 ?\)

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