Statistics: Hypothesis Testing Overview
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Questions and Answers

What is the sample standard deviation of the customer expenditure?

  • R0.75 (correct)
  • R0.50
  • R1.00
  • R1.25

The null hypothesis states that there is a significant difference between the parameter values.

False (B)

At a 99% confidence level, what is the Z-score used in hypothesis testing?

2.58

The _____ hypothesis is not true if there is sufficient evidence against it.

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

Match the following components with their definitions:

<p>Z-score = A measure of standard deviations from the mean Confidence Level = Probability that the true parameter lies within the interval Null Hypothesis = Hypothesis that proposes no difference or effect Alternative Hypothesis = Hypothesis that proposes a difference or effect exists</p> Signup and view all the answers

What would be the conclusion if the test statistic is Z = -2.5 at 1% level of significance?

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

A two-tailed test checks for differences in both directions (greater and lesser).

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

What is the null hypothesis in the case of Mr.Cake's average daily bread sales?

<p>Ho: μ = 1500</p> Signup and view all the answers

In a one-tailed hypothesis test with a significance level of 0.05, what is the critical Z value for rejection in the left tail?

<p>-1.645 (B)</p> Signup and view all the answers

The null hypothesis is rejected if the test statistic is greater than the critical value in a one-tailed test.

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

What is the significance level used in the hypothesis testing example given above?

<p>0.05</p> Signup and view all the answers

If a textile company's claim is that the average strength of their fabric is at least 22.7 kg, then the null hypothesis is Ho: μ __________ 22.7 kg.

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

Match the following values with their corresponding confidence levels:

<p>1.65 = 90% confidence level 1.96 = 95% confidence level 2.58 = 99% confidence level 0.05 = Significance level for 95% confidence</p> Signup and view all the answers

What conclusion is made if the test statistic calculated is -2.48 when testing the fabric strength claim?

<p>There is sufficient evidence to conclude the average strength is less than 22.7 kg. (D)</p> Signup and view all the answers

In hypothesis testing, the alternative hypothesis is denoted as Ha: μ ≤ 22.7 kg when testing against the company's claim.

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

What is the test statistic for the example provided in the content?

<p>-2.48</p> Signup and view all the answers

What Z-value corresponds to a 95% confidence level?

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

The Z-table provides probabilities for Z-values greater than or equal to zero only.

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

What is the Z-value for a 99% confidence level?

<p>2.58</p> Signup and view all the answers

For estimating a finite population when σ is known, we use the ______ method.

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

Match the following confidence levels with their corresponding Z-values:

<p>90% = 1.65 95% = 1.96 99% = 2.58</p> Signup and view all the answers

If the population standard deviation (σ) is unknown and the sample size is greater than 30, which method is used for estimation?

<p>T-method (C)</p> Signup and view all the answers

In an infinite population, if σ is known, we still estimate using the T-distribution.

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

Which Z-value indicates an area to the left of 0.5 in the standard normal distribution?

<p>0</p> Signup and view all the answers

The smart packaging company is trying to estimate the average ______ per customer.

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

What value from the Z-table corresponds to a Z-score of 1.0?

<p>0.3413 (B)</p> Signup and view all the answers

Flashcards

One-tailed test

A hypothesis test where the region of rejection is on only one side of the sampling distribution.

Standard Normal Table

A table that shows the probabilities associated with different values of a standard normal variable.

90% confidence level

A level of confidence where there is a 90% probability that the true population parameter lies within the calculated confidence interval.

Left-tailed test

A one-tailed hypothesis test where the null hypothesis is rejected if the sample mean is significantly less than the hypothesized population mean.

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Right-tailed test

A one-tailed hypothesis test where the null hypothesis is rejected if the sample mean is significantly greater than the hypothesized population mean.

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95% confidence level

A level of confidence where there is a 95% probability that the true population parameter lies within the calculated confidence interval.

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Null Hypothesis (Ho)

A statement of no effect or no difference in a hypothesis test, often assumed to be true.

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99% confidence level

A level of confidence where there is a 99% probability that the true population parameter lies within the calculated confidence interval.

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Alternative Hypothesis (Ha)

A statement that contradicts the null hypothesis, representing the effect you are trying to find.

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Estimating when σ is known

Calculating confidence intervals for population means when the population standard deviation (σ) is known.

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Estimating when σ is unknown (n > 30)

Calculating confidence intervals for population means when the population standard deviation (σ) is unknown, but the sample size (n) is greater than 30.

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Significance Level (α)

The probability of rejecting a true null hypothesis.

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Critical Value (Z critical)

The value of the test statistic that separates the region of acceptance from the region of rejection.

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Population Standard Deviation (σ)

A measure of the spread of data points around the population mean.

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Confidence Interval

A range of values that is likely to contain the true population parameter.

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Test Statistic

A numerical value calculated from sample data to determine whether to reject the null hypothesis.

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Confidence Level

The probability that an interval estimate contains the true population parameter.

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Standard Error

The standard deviation of the sampling distribution of a point estimator.

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Confidence Interval

A range of values that likely contains the true average of a population, calculated from a sample.

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Sample Standard Deviation (s)

A measure of the spread of data points in a sample.

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Hypothesis Testing

A statistical method for testing an assumption (hypothesis) about a population parameter.

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Null Hypothesis (H0)

A statement of no effect or no difference, which is initially assumed to be true in hypothesis testing.

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Alternative Hypothesis (H1)

The statement that contradicts the null hypothesis; the statement you are trying to find evidence for.

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Two-Tailed Test

A hypothesis test where the alternative hypothesis indicates a difference in either direction. Reject null if result is significantly high or low.

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Level of Significance (α)

The probability of rejecting a true null hypothesis, set by the researcher.

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Rejection Region

The range of test statistic values that lead to the rejection of the null hypothesis.

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Sample Size (n)

The number of observations in a sample drawn from a population.

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Z-score

A measure of how many standard deviations a data point is from the mean of the population.

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Finite Population

A population with a specific fixed size.

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Finite Population Correction Factor

Modifies the standard error in cases of finite population.

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Study Notes

One-Tailed Hypothesis Tests

  • A one-tailed test focuses on one direction of the alternative hypothesis.
  • The critical region is located in one tail of the distribution.
  • Significance level (α) is the probability of rejecting the null hypothesis when it is true. In one-tailed tests, the significance level is applied entirely to one tail of the distribution.
  • The decision rule depends on whether the test is left-tailed or right-tailed.

Two-Tailed Hypothesis Tests

  • A two-tailed test considers deviations from the null hypothesis in both directions.
  • The critical region is split between the two tails of the distribution.
  • Significance level (α) is divided between the two tails.
  • The decision rule involves comparing the test statistic to both upper and lower critical values.

Hypothesis Testing

  • A procedure for evaluating a claim about a population parameter.
  • Hypotheses are statements about the population parameter.
  • The objective is to decide if the evidence supports the claim.
  • Null hypothesis (H₀) is the statement of no effect or no difference.
  • Alternative hypothesis (Hₐ) is the claim being tested.

Confidence Intervals

  • An interval estimate of a population parameter calculated from a sample statistic.
  • Confidence level represents the probability that the interval contains the true population parameter.
  • Confidence level is expressed as a percentage, e.g., 90%, 95%, 99%.
  • Common confidence levels have corresponding critical values. These critical values define the range within which the population parameter value is likely to fall. The critical values depend on the confidence level to be achieved.

Sample Size Determination

  • Determining the appropriate sample size needed for a given level of accuracy.
  • Factors such as confidence level, desired margin of error, and population standard deviation or sample standard deviation play a critical role in this process. The sample size required is influenced by both the desired precision of the calculation and the confidence level.

Standard Error

  • Standard deviation of a sampling distribution of a sample statistic
  • A function of the standard deviation of the population and the sample size; smaller sample sizes tend to give greater variability, leading to a higher standard error

Examples of Hypothesis Testing

  • Testing average fabric strength
  • Average spending per customer
  • Average number of breads sold daily
  • Number of daily newspaper readers.

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One-tailed Test PDF

Description

This quiz covers the fundamentals of hypothesis testing, including one-tailed and two-tailed tests. Learn how significance levels and decision rules are applied in different testing scenarios. Test your understanding of key concepts related to evaluating claims about population parameters.

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