Z-test vs T-test: Hypothesis Testing for Means

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Questions and Answers

What are the two specific test statistics used for hypothesis testing concerning means?

z-test and t-test

If the sample size is large where $n \geq 30$ and the population standard deviation ($\sigma$) is known, you should use t-test.

False (B)

In the formula for the z-value, what does $\bar{x}$ represent?

sample mean

In the formula for the z-value, what does $\mu$ represent?

<p>population mean</p> Signup and view all the answers

The t-test is used when $n < 30$, the population is normal or nearly normal, and sample standard deviation (s) is known.

<p>False (B)</p> Signup and view all the answers

What is the formula for degrees of freedom?

<p>n - 1 or df = n-1</p> Signup and view all the answers

In the Zcom formula, what does $\hat{p}$ represent?

<p>sample proportion</p> Signup and view all the answers

In the Zcom formula, what does $p$ represent?

<p>hypothesized value of the population proportion</p> Signup and view all the answers

Flashcards

When do you use a z-test?

A test used when the sample size (n) is large (≥ 30) and the population standard deviation (σ) is known.

When do you use a t-test?

A test used when the sample size (n) is small (< 30), the population is normal or nearly normal, and the population standard deviation (s) is unknown.

What is x̄?

Sample mean

What is μ?

Population mean

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What is n?

Number of values in the sample

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What is σ?

Population standard deviation

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What is s?

Sample standard deviation

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Formula for degrees of freedom (df)

n - 1

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What is p̂?

Sample proportion = x/n

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What is p?

Hypothesized value of the population proportion.

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Study Notes

  • Two test statistics are used for hypothesis testing concerning means: z-test and t-test.

Z-test

  • Use the z-test if the sample size n ≥ 30 and the population standard deviation (σ) is known.
  • The formula for finding the z-value is:
  • Variable definitions:
    • x = sample mean
    • μ = population mean
    • n = sample size
    • σ = population standard deviation

T-test

  • Use the t-test if n < 30, the population is normal or nearly normal, and the sample standard deviation (s) is unknown.
  • The formula for the t-value is:
  • Variable definitions:
    • x = sample mean
    • μ = population mean
    • n = sample size
    • s = population standard deviation
  • The degrees of freedom is n - 1 or df = n - 1.

Decision Making for Hypothesis Testing

  • Reject H₀ ("Sufficient"):
    • When H₀ is rejected, there is sufficient evidence at the alpha level of significance to reject the claim.
  • Fail to Reject H₀ ("Insufficient"):
    • When H₀ is not rejected, there is insufficient evidence at the alpha level of significance to reject the claim.
  • Hₐ ("Support"):
    • If there is sufficient evidence at the alpha level of significance to support the claim
  • If there is insufficient evidence at the alpha level of significance to support the claim

Z-test Statistic for Proportion

  • z-test statistic for proportion:
    • Zcom =
  • Variable definitions:
    • Zcom = the z-test statistic for proportion
    • = the sample proportion
    • p = the hypothesized value of the population proportion
    • n = the sample size or the number of observations in the sample
    • q = 1 - p

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