Hypothesis Testing Overview

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Questions and Answers

What is the null hypothesis in the context of the research question regarding psychology students' average IQ?

  • μ > 100
  • μ ≠ 100
  • μ < 100
  • μ = 100 (correct)

Which significance level is commonly chosen in hypothesis testing?

  • α = 0.20
  • α = 0.01 (correct)
  • α = 0.05 (correct)
  • α = 0.10

What type of hypothesis test is appropriate for determining the average IQ of psychology students compared to the general population?

  • Paired t-test
  • One-sample t-test (correct)
  • One-sample z-test
  • Two-sample t-test

If the calculated test statistic is less than or equal to the critical value, what is the decision?

<p>Fail to reject the null hypothesis (B)</p> Signup and view all the answers

What does effect size indicate in hypothesis testing?

<p>The magnitude of the effect or difference between groups (D)</p> Signup and view all the answers

In the context of hypothesis testing, which of the following best describes a Type I error?

<p>Rejecting the null hypothesis when it is true (A)</p> Signup and view all the answers

What is the critical value for the one-sample t-test if the significance level is α = 0.05 and the test statistic is t = 3.45?

<p>3.06 (D)</p> Signup and view all the answers

Which statement about effect size is correct?

<p>It allows comparisons across studies. (A)</p> Signup and view all the answers

What is the primary purpose of formulating a null hypothesis?

<p>To provide a statement of no effect or difference (B)</p> Signup and view all the answers

In hypothesis testing, what does the alternative hypothesis represent?

<p>The assumption of an existing effect or difference (B)</p> Signup and view all the answers

Which of the following is NOT a step in the hypothesis testing process?

<p>Calculate a confidence interval (C)</p> Signup and view all the answers

What role does the p-value play in hypothesis testing?

<p>It quantifies the strength of the evidence against the null hypothesis (A)</p> Signup and view all the answers

What happens if the p-value is very small while testing a hypothesis?

<p>We reject the null hypothesis in favor of the alternative (A)</p> Signup and view all the answers

Which of the following describes a Type I error in hypothesis testing?

<p>Rejecting a true null hypothesis (B)</p> Signup and view all the answers

In hypothesis testing, what does a significance level (alpha) typically define?

<p>The probability of incorrectly rejecting a true null hypothesis (A)</p> Signup and view all the answers

Which statement about hypothesis testing is FALSE?

<p>Hypothesis testing can prove a hypothesis definitively. (D)</p> Signup and view all the answers

What does the null hypothesis (H₀) state in a study comparing sample and population means?

<p>The sample mean is equal to the hypothesized population mean. (A)</p> Signup and view all the answers

Which statement best describes the alternative hypothesis (H₁ or Hₐ)?

<p>It represents the prediction researchers aim to support. (A)</p> Signup and view all the answers

When would a one-tailed test be appropriately used?

<p>When there is a strong theoretical reason to expect a directional effect. (C)</p> Signup and view all the answers

What does a significance level (α) of 0.05 imply in hypothesis testing?

<p>There is a 5% chance of making a Type I error. (D)</p> Signup and view all the answers

What is the relationship between significance level (α) and Type I and Type II errors?

<p>Higher α levels lead to increased likelihood of Type I errors. (C)</p> Signup and view all the answers

What are critical values in hypothesis testing?

<p>They are points that decide whether to accept H₀ or H₁. (D)</p> Signup and view all the answers

In a two-tailed test with α = 0.05, what are the critical values in a z-distribution?

<p>-1.96 and 1.96 (A)</p> Signup and view all the answers

Which condition leads to the acceptance of the null hypothesis?

<p>When the test statistic is less than the critical value. (D)</p> Signup and view all the answers

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Study Notes

### Hypothesis Testing

  • Hypothesis testing is a statistical method used to make inferences about populations based on sample data.
  • The core principle is to assume a null hypothesis (no effect or difference) and use data to determine if this assumption is likely to be true.
  • This method helps determine if observed patterns in sample data reflect true patterns in the larger population or are due to random chance.
  • Key steps:
    • Formulate a null hypothesis (H₀) and an alternative hypothesis (H₁).
    • Collect data from a sample.
    • Calculate a test statistic based on the data.
    • Determine the probability of obtaining such a test statistic assuming the null hypothesis is true.
    • Decide whether to reject or accept the null hypothesis based on this probability.

Alternative Hypothesis

  • The alternative hypothesis (H₁) is the one the researcher seeks to support.
  • It usually represents the opposite of the null hypothesis and suggests an effect or difference.
  • Types of alternative hypotheses:
    • Two-tailed (non-directional): States that there is a difference, but doesn't specify the direction (e.g., μ₁ ≠ μ₂).
    • One-tailed (directional): Specifies the direction of the difference (e.g., μ₁ > μ₂ or μ₁ < μ₂).
  • The choice between one-tailed and two-tailed tests depends on the research question and prior knowledge.

### Significance Level

  • The significance level (α) represents the probability of rejecting the null hypothesis when it is actually true (Type I error).
  • Common values for α are 0.05 and 0.01.
  • Selecting α is a trade-off:
    • A smaller α reduces the chance of Type I errors but increases the chance of Type II errors (failing to reject a false null hypothesis).
    • A larger α does the opposite.

Critical Values

  • Critical values are the boundaries of the rejection region in a distribution.
  • If the test statistic falls outside these boundaries (beyond the critical values), the null hypothesis is rejected.
  • Example: For a two-tailed test with α = 0.05 in a z-distribution, the critical values are ±1.96.

Decision Rules

  • p-value < α: Reject the null hypothesis.
  • p-value ≥ α: Fail to reject the null hypothesis.

### Effect Size

  • Effect size is a measure of the strength of a phenomenon.
  • It quantifies the difference between groups or the strength of a relationship between variables.
  • Provides insight into the practical significance of a result beyond its statistical significance.
  • Allows for comparison across studies, even with different sample sizes.
  • Less affected by sample size than p-values.

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