Hypothesis testing

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Questions and Answers

In hypothesis testing, what is the initial assumption made about a hypothesis?

  • It is neither true nor false until tested.
  • It is irrelevant to the testing process.
  • It is false until proven true.
  • It is true until proven otherwise. (correct)

Why is the null hypothesis often formulated as a statement of 'no difference'?

  • To simplify the mathematical calculations.
  • To align with the alternative hypothesis.
  • To provide a clear target for rejection. (correct)
  • To ensure it is always accepted.

What does it mean to commit a Type I error in hypothesis testing?

  • Failing to reject a false alternative hypothesis.
  • Rejecting a true null hypothesis. (correct)
  • Rejecting a true alternative hypothesis.
  • Accepting a false null hypothesis.

Under what circumstance is a Type II error committed?

<p>When the null hypothesis is false, and we fail to reject it. (B)</p> Signup and view all the answers

In a one-sided hypothesis test, what does the alternative hypothesis specify?

<p>That the parameter is entirely above or entirely below the value specified by the null hypothesis. (D)</p> Signup and view all the answers

How does a two-sided test differ from a one-sided test in hypothesis testing?

<p>A two-sided test considers values on both sides of the null hypothesis. (B)</p> Signup and view all the answers

If $H_0 : \mu = 100$, which of the following alternative hypotheses ($H_a$) represents a two-sided test?

<p>$H_a : \mu \neq 100$ (C)</p> Signup and view all the answers

What does the level of significance, denoted by alpha ($\alpha$), represent in hypothesis testing?

<p>The probability of committing a Type I error. (D)</p> Signup and view all the answers

What does the critical region in hypothesis testing represent?

<p>The range of values for the test statistic that lead to the rejection of the null hypothesis. (B)</p> Signup and view all the answers

What is the first step in hypothesis testing?

<p>State the null and alternative hypotheses. (B)</p> Signup and view all the answers

After stating the null and alternative hypotheses, what is the next step in hypothesis testing?

<p>Specify the level of significance and the sample size. (D)</p> Signup and view all the answers

If a researcher sets $\alpha = 0.05$, what is the implication for the study's outcome?

<p>There is a 5% chance of incorrectly rejecting a true null hypothesis. (C)</p> Signup and view all the answers

In a study comparing two population means ($\mu_1$ and $\mu_2$), the null hypothesis is $H_0 : \mu_1 = \mu_2$. Which alternative hypothesis ($H_a$) represents a two-sided test?

<p>$H_a : \mu_1 \neq \mu_2$ (C)</p> Signup and view all the answers

What is the purpose of computing the test statistic in hypothesis testing?

<p>To determine whether the sample data sufficiently contradicts the null hypothesis. (D)</p> Signup and view all the answers

Which of the following outcomes would lead to the rejection of the null hypothesis?

<p>The p-value is less than alpha ($\alpha$). (D)</p> Signup and view all the answers

Flashcards

Hypothesis

A tentative theory that may or may not be true, but is initially assumed to be true until new evidence suggests otherwise.

Null Hypothesis

The hypothesis of 'no difference,' formulated to be rejected.

Alternative Hypothesis

A hypothesis that contradicts the null hypothesis. It is supported if the null hypothesis is rejected.

Type I Error

Occurs when the null hypothesis is rejected when it is actually true.

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Type II Error

Occurs when the null hypothesis is accepted when it is actually false.

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One-Sided Test

Specifies that the population parameter is either entirely above or entirely below the specified value.

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Two-Sided Test

Specifies the population parameter can lie on either side of the value specified.

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Level of Significance (alpha)

The probability of committing a Type I error.

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Critical Region

The set of test statistic values that lead to rejecting the null hypothesis.

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Basic Steps in Hypothesis Testing

State hypotheses, specify significance, choose test, define critical region, compute statistic, make a decision.

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Study Notes

  • A hypothesis is a statement or tentative theory, that may or may not be true.
  • A hypothesis is assumed true until new evidence suggests otherwise.
  • Hypotheses can be proposed from preliminary observations, guesses, or previous experiences.

Types of Hypothesis

  • The null hypothesis, denoted by Ho, states there is "no difference."
  • The null hypothesis is formulated for the purpose of being rejected.
  • The alternative hypothesis, denoted by Ha or H1, contradicts the null hypothesis.
  • If the null hypothesis is rejected, the alternative hypothesis is supported.
  • The alternative hypothesis is the operational statement of the experimenter's research hypothesis.

Types of Errors

  • A Type I error occurs when the null hypothesis is rejected when it is actually true.
  • A Type II error occurs when the null hypothesis is accepted when it is false.
  • If Ho is true and is accepted, there is a correct decision.
  • If Ho is false and is rejected, there is a correct decision.

Types of Tests

  • In a one-sided test, the alternative hypothesis specifies that the unknown population parameter is entirely above or entirely below the specified value of Ho.
  • A one-sided test is also called a one-tailed or directional test.
  • In a two-sided test, the alternative hypothesis specifies that the unknown population parameter can lie on either side of the value specified by Ho.
  • A two-sided test is also called a two-tailed or non-directional test.

Examples

  • One sided test
    • Ho : μ = 100, Ha : μ < 100
    • Ho : μ = 100, Ha : μ > 100
  • Two-sided test
    • Ho : μ = 100, Ha : μ ≠ 100
    • Ho : μ₁ = μ₂, Ha : μ₁ - μ₂ ≠ 0

Level of Significance

  • The probability of committing a Type I error is denoted by alpha (α).
  • The probability of committing a Type II error is denoted by beta (β) = 1 - α.

Critical Region

  • Critical region refers to the set of all values of the test statistics that would cause the null hypothesis to be rejected.

Basic Steps in Hypothesis Testing

  • State the null hypothesis (Но) and the alternative hypothesis (Ha).
  • Specify the level of significance α and the sample size n.
  • Determine the test statistic.
  • Define the critical region or decision rule.
  • Compute the test statistics for a sample size n.
  • Make a decision/conclusion.

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