Explain how to find critical values for a t-distribution.
Table of contents
- 1. Intro to Stats and Collecting Data55m
- 2. Describing Data with Tables and Graphs1h 55m
- 3. Describing Data Numerically1h 45m
- 4. Probability2h 16m
- 5. Binomial Distribution & Discrete Random Variables2h 33m
- 6. Normal Distribution and Continuous Random Variables1h 38m
- 7. Sampling Distributions & Confidence Intervals: Mean1h 53m
- 8. Sampling Distributions & Confidence Intervals: Proportion1h 12m
- 9. Hypothesis Testing for One Sample2h 19m
- 10. Hypothesis Testing for Two Samples3h 26m
- 11. Correlation1h 6m
- 12. Regression1h 35m
- 13. Chi-Square Tests & Goodness of Fit1h 57m
- 14. ANOVA1h 0m
9. Hypothesis Testing for One Sample
Steps in Hypothesis Testing
Problem 7.1.51a
Textbook Question
Writing Hypotheses: Backpack Manufacturer A backpack manufacturer claims that the mean life of its competitor’s backpacks is less than 5 years. You are asked to perform a hypothesis test to test this claim. How would you write the null and alternative hypotheses when
a. you represent the manufacturer and want to support the claim?

1
Understand the context: The manufacturer claims that the mean life of the competitor's backpacks is less than 5 years. This is a one-tailed hypothesis test because the claim is directional ('less than').
Define the null hypothesis (H₀): The null hypothesis always represents the status quo or no effect. In this case, it would state that the mean life of the competitor's backpacks is greater than or equal to 5 years. Mathematically, H₀: μ ≥ 5, where μ represents the mean life of the competitor's backpacks.
Define the alternative hypothesis (H₁): The alternative hypothesis represents the claim being tested. Since the manufacturer claims that the mean life is less than 5 years, the alternative hypothesis is H₁: μ < 5.
Verify the direction of the test: Since the alternative hypothesis uses '<', this is a left-tailed test. This will influence the critical region and p-value calculation during the hypothesis test.
Summarize the hypotheses: Null hypothesis (H₀): μ ≥ 5. Alternative hypothesis (H₁): μ < 5. These hypotheses will guide the statistical test to determine whether there is sufficient evidence to support the manufacturer's claim.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Null Hypothesis (H0)
The null hypothesis is a statement that indicates no effect or no difference, serving as a default position in hypothesis testing. In this context, it would assert that the mean life of the competitor's backpacks is equal to or greater than 5 years. This hypothesis is tested against the alternative hypothesis to determine if there is enough evidence to reject it.
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Step 1: Write Hypotheses
Alternative Hypothesis (H1)
The alternative hypothesis represents the claim or effect that the researcher aims to support. In this scenario, it would state that the mean life of the competitor's backpacks is less than 5 years. This hypothesis is what the manufacturer wants to prove, and it is accepted if the evidence from the data is strong enough to reject the null hypothesis.
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Step 1: Write Hypotheses
Hypothesis Testing
Hypothesis testing is a statistical method used to make decisions about a population based on sample data. It involves calculating a test statistic and comparing it to a critical value to determine whether to reject the null hypothesis. The process includes setting significance levels, collecting data, and interpreting results to draw conclusions about the claims being tested.
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Step 1: Write Hypotheses
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