Hypothesis Testing Overview

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Questions and Answers

What is typically used to determine the area of rejection in hypothesis testing?

  • Standard deviation of the sample
  • Sample size determination
  • Confidence interval range
  • P-value of the test statistic (correct)

What is the level of significance generally used in hypothesis testing?

  • 0.1
  • 0.25
  • 0.05 (correct)
  • 0.01

Which statistical tests belong to the T-test family?

  • Independent samples T-test and Paired samples T-test (correct)
  • Chi-square test and Mann-Whitney U test
  • One-sample T-test and ANOVA
  • Regression analysis and Correlation analysis

Which of the following is NOT a purpose of statistical tests in bioepidemiology?

<p>Determining causality (A)</p> Signup and view all the answers

In formulating a hypothesis, which statement is correctly framed?

<p>Increased exposure leads to decreased incidence. (C)</p> Signup and view all the answers

What is the significance of defining the Area of Rejection in hypothesis testing?

<p>It identifies the conditions under which the null hypothesis is considered false. (D)</p> Signup and view all the answers

When selecting a level of significance (α) in hypothesis testing, what does it represent?

<p>The probability of rejecting the null hypothesis when it is true. (B)</p> Signup and view all the answers

Which of the following correctly describes the formulation of the null hypothesis (Ho) and alternative hypothesis (Ha)?

<p>Ho is usually a value that is assumed to be true, while Ha suggests an alternative explanation. (D)</p> Signup and view all the answers

Which statistic is most appropriate for comparing the means of a sample to a known population mean when the sample size is large?

<p>Z-test (A)</p> Signup and view all the answers

In the example where a teacher claims the mean score of students in his class is greater than 82, which type of test should be used?

<p>One-tailed t-test (C)</p> Signup and view all the answers

What is the correct definition of the Area of Rejection in hypothesis testing?

<p>The set of values that leads to the rejection of the null hypothesis (A)</p> Signup and view all the answers

How is the level of significance (α) important in hypothesis testing?

<p>It indicates the probability of making a Type I error (C)</p> Signup and view all the answers

For a paired t-test, what is the formula for the degrees of freedom (df)?

<p>df = n - 1 (C)</p> Signup and view all the answers

What type of t-test is used when comparing two independent groups?

<p>Unpaired t-test (B)</p> Signup and view all the answers

In hypothesis formulation, what does the null hypothesis (H0) typically state?

<p>There is no effect or difference (A)</p> Signup and view all the answers

If the critical value of a two-tailed test at the 1% significance level is ±2.845, what would be the decision if the test statistic is 3.0?

<p>Reject the null hypothesis (D)</p> Signup and view all the answers

What is an incorrect interpretation of a two-tailed significance level of 0.05?

<p>All differences will be significant if p &lt; 0.05 (D)</p> Signup and view all the answers

What is the role of the test statistic in hypothesis testing?

<p>To quantify how far a sample statistic is from the null hypothesis (D)</p> Signup and view all the answers

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Study Notes

Hypothesis Testing

  • Hypothesis testing is a statistical method used to determine whether there is enough evidence to support a claim about a population.
  • There are two types of hypotheses:
    • Null hypothesis (H0): It states that there is no significant difference between the groups being compared.
    • Alternative hypothesis (Ha): It states that there is a significant difference between the groups being compared.
  • The level of significance (α) is the probability of rejecting the null hypothesis when it is actually true.
  • The area of rejection is the region in the sampling distribution where the test statistic falls, leading to the rejection of the null hypothesis.
  • The test statistic is a value that is calculated from the sample data to test the hypothesis.
  • The conclusion is based on the comparison of the test statistic to the critical value. If the test statistic falls within the area of rejection, the null hypothesis is rejected.

Example #4

  • The teacher claims that the mean score of students in his class is greater than 82.
  • The null hypothesis (H0) is that the mean score is not greater than 82.
  • The alternative hypothesis (Ha) is that the mean score is greater than 82.
  • The level of significance (α) is 0.05.
  • The test statistic used is the z-test.
  • The critical value for a one-tailed test with α = 0.05 is 1.645.
  • The test statistic is calculated to be 3.23.
  • Since 3.23 is greater than 1.645, the null hypothesis is rejected.
  • The conclusion is that there is enough evidence to support the teacher's claim.

Example #5

  • The null hypothesis (H0) is that there is no significant difference between the two groups.
  • The alternative hypothesis (Ha) is that there is a significant difference between the two groups.
  • The level of significance (α) is 0.01.
  • The test statistic used is the unpaired/independent t-test.
  • The critical value for a two-tailed test with α = 0.01 is ±2.845.
  • The area of rejection is the region in the sampling distribution where the test statistic falls outside the range of -2.845 and +2.845.

Choosing Statistical Tests

  • Parametric statistical tests require data to be normally distributed, while non-parametric tests do not.
  • The type of statistical test used depends on the type of data and the research question. Choices for parametric tests include:
    • Chi-square family
    • T-test family
    • Correlation family
  • Parametric tests are used when the data is continuous and the goal is to compare or analyze relationships between variables.

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