Family-wise Error Rate and Bonferroni Adjustment Quiz
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Questions and Answers

What is the purpose of using the Scheffé adjustment for multiple comparisons?

  • To increase the power of each contrast
  • To control the family-wise error rate (correct)
  • To simplify the calculation of the test statistics
  • To decrease the p-value of each contrast
  • How does the Scheffé adjustment affect the p-value of each contrast?

  • It increases the p-value (correct)
  • It decreases the p-value
  • It makes it impossible to calculate the p-value
  • It has no effect on the p-value
  • What is the key assumption made when applying the Scheffé adjustment?

  • Independence of data points
  • Normal distribution of data
  • Homoscedasticity of residuals
  • Performing all possible contrasts (correct)
  • Which method controls the family-wise error rate in multiple comparisons?

    <p>Scheffé adjustment</p> Signup and view all the answers

    In Example 5.3.1, how did the contrasts tested differ from those tested in examples 4.2.1 and 4.2.2?

    <p>They were run simultaneously with adjustments for multiple testing</p> Signup and view all the answers

    When using the Scheffé adjustment, what change is made to the degrees of freedom for calculating test statistics?

    <p>+g - 1 degrees of freedom</p> Signup and view all the answers

    What is the primary purpose of starter bacteria in cheese production?

    <p>To initiate the fermentation process</p> Signup and view all the answers

    Which bacteria were not intentionally added during the cheese production process?

    <p>Nonstarter bacteria</p> Signup and view all the answers

    How many cheeses were made with standard starter bacteria only?

    <p>8</p> Signup and view all the answers

    Which of the following treatments was NOT included in the experiment?

    <p>Strain C only</p> Signup and view all the answers

    What is the primary reason for studying the effects of nonstarter bacteria on cheese quality?

    <p>To understand their influence on cheese quality</p> Signup and view all the answers

    How many cheeses were made with both strains A and B?

    <p>2</p> Signup and view all the answers

    What is the purpose of Dunnett's method?

    <p>To compare each group to the control group</p> Signup and view all the answers

    Which function from the DescTools package can be used to perform Dunnett's method?

    <p><code>DunnettTest()</code></p> Signup and view all the answers

    In the example code DunnettTest(freeAminoAcid ~ strain, data = CheeseAminoAcid, control = "none"), what does the control = "none" argument specify?

    <p>It sets the control group to be the group named &quot;none&quot;</p> Signup and view all the answers

    Based on the output, which bacteria group(s) are significantly different from the control group ("none") with respect to the mean total free amino acids?

    <p>AB-none only</p> Signup and view all the answers

    What does the lwr.ci column in the output represent?

    <p>The lower bound of the 95% confidence interval for the difference</p> Signup and view all the answers

    What is the purpose of the Multiple Comparisons with the Best (MCB) method?

    <p>To compare each group to the best performing group</p> Signup and view all the answers

    What is the purpose of the rbind() function in the code snippet?

    <p>To combine the contrasts into a single matrix</p> Signup and view all the answers

    Which of the following statements about the use of Fisher's LSD method on the RatLiverWeight data is correct?

    <p>It is not appropriate to use Fisher's LSD method since it does not control the family-wise error rate</p> Signup and view all the answers

    What is the purpose of the pf() function call in the code snippet?

    <p>To calculate the p-value for the Scheffe adjustment</p> Signup and view all the answers

    What is the family-wise error rate?

    <p>The probability of making a type I error in at least one of the multiple comparisons</p> Signup and view all the answers

    In the Bonferroni method, how is the adjusted p-value for each test calculated?

    <p>The p-value is multiplied by the number of tests (K)</p> Signup and view all the answers

    In the Holm method, which p-value is compared to $\alpha/K$ first?

    <p>The smallest p-value</p> Signup and view all the answers

    If the Bonferroni method is used to adjust for multiple comparisons, what happens to the family-wise error rate?

    <p>The family-wise error rate is controlled at $\alpha$</p> Signup and view all the answers

    Which statement about the Holm method is true?

    <p>It is more powerful than the Bonferroni method when all null hypotheses are true</p> Signup and view all the answers

    In Example 5.2.1, if the Bonferroni adjustment is used with $\alpha = 0.05$, how many contrasts would be considered significant?

    <p>3</p> Signup and view all the answers

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