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Ch. 8 - Hypothesis Testing
Triola - Elementary Statistics 14th Edition
Triola14th EditionElementary StatisticsISBN: 9780137366446Not the one you use?Change textbook
Chapter 8, Problem 8.CQQ.2

Discarded Plastic Find the test statistic used for the hypothesis test described in Exercise 1.

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Step 1: Identify the type of hypothesis test being conducted. Determine whether it is a one-sample test, two-sample test, or another type of test (e.g., t-test, z-test, chi-square test). This information is crucial for selecting the correct test statistic formula.
Step 2: Define the null hypothesis (H₀) and the alternative hypothesis (H₁). The null hypothesis typically represents no effect or no difference, while the alternative hypothesis represents the claim being tested.
Step 3: Gather the necessary data for the test. This includes sample size (n), sample mean (x̄), population mean (μ), standard deviation (σ or s), and any other relevant parameters depending on the test type.
Step 4: Select the appropriate formula for the test statistic based on the type of test. For example, for a z-test, the formula is (x¯-μ)σn, and for a t-test, the formula is (x¯-μ)sn. Ensure you use the correct formula for the given scenario.
Step 5: Plug the values from the data into the formula and simplify the expression to compute the test statistic. This value will be used to compare against the critical value or p-value to make a decision regarding the hypothesis.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Hypothesis Testing

Hypothesis testing is a statistical method used to make decisions about a population based on sample data. It involves formulating a null hypothesis (H0) and an alternative hypothesis (H1), then using sample data to determine whether to reject H0. The process includes calculating a test statistic, which helps assess the strength of the evidence against H0.
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Step 1: Write Hypotheses

Test Statistic

A test statistic is a standardized value that is calculated from sample data during a hypothesis test. It quantifies the difference between the observed sample statistic and the hypothesized population parameter, relative to the variability in the sample. Common test statistics include the z-score for large samples and the t-score for smaller samples, each used to determine the significance of the results.
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Step 2: Calculate Test Statistic

Significance Level

The significance level, often denoted as alpha (α), is the threshold used to determine whether to reject the null hypothesis. It represents the probability of making a Type I error, which occurs when the null hypothesis is incorrectly rejected. Common significance levels are 0.05 and 0.01, indicating a 5% or 1% risk of concluding that a difference exists when there is none.
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Step 4: State Conclusion Example 4
Related Practice
Textbook Question

Hypothesis Test for Lightning Deaths Refer to the sample data given in Cumulative Review Exercise 1 and consider those data to be a random sample of annual lightning deaths from recent years. Use those data with a 0.01 significance level to test the claim that the mean number of annual lightning deaths is less than the mean of 72.6 deaths from the 1980s. If the mean is now lower than in the past, identify one of the several factors that could explain the decline.

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Textbook Question

Robust Explain what is meant by the statements that the t test for a claim about μ is robust, but the (chi)^2 test for a claim about σ is not robust.

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Textbook Question

Discarded Plastic


What distribution is used for the hypothesis test described in Exercise 1?

For the hypothesis test described in Exercise 1, is it necessary to determine whether the 62 weights appear to be from a population having a normal distribution? Why or why not?

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Textbook Question

Lightning Deaths The graph in Cumulative Review Exercise 5 was created by using data consisting of 242 male deaths from lightning strikes and 64 female deaths from lightning strikes. Assume that these data are randomly selected lightning deaths and proceed to test the claim that the proportion of male deaths is greater than . Use a 0.01 significance level. Any explanation for the result?

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Textbook Question

Discarded Plastic Data Set 42 “Garbage Weight” includes weights (pounds) of discarded plastic from 62 different households. Those 62 weights have a mean of 1.911 pounds and a standard deviation of 1.065 pounds. We want to use a 0.05 level of significance to test the claim that this sample is from a population with a mean less than 2.000 pounds. Identify the null hypothesis and alternative hypothesis.

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Textbook Question

Type I Error and Type II Error


a. In general, what is a type I error? In general, what is a type II error?

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