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Ch. 10 - Chi-Square Tests and the F-Distribution
Larson - Elementary Statistics: Picturing the World 8th Edition
Larson8th EditionElementary Statistics: Picturing the WorldISBN: 9780137493470Not the one you use?Change textbook
Chapter 10, Problem 10.4.3

Describe the difference between the variance between samples MSB and the variance within samples MSW.

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The variance between samples (MSB) measures the variability of the sample means around the overall mean. It reflects how much the group means differ from each other.
The variance within samples (MSW) measures the variability of individual data points within each sample group. It reflects how much the data points within a single group differ from their group mean.
Mathematically, MSB is calculated as the sum of squared differences between each group mean and the overall mean, weighted by the sample size of each group, divided by the degrees of freedom between groups.
MSW is calculated as the sum of squared differences between each data point and its respective group mean, divided by the degrees of freedom within groups.
In the context of ANOVA, MSB is used to assess differences between groups, while MSW is used to assess variability within groups. A larger MSB relative to MSW suggests significant differences between group means.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Variance Between Samples (MSB)

Mean Square Between (MSB) refers to the variance that measures the differences between the means of different groups or samples. It is calculated by taking the sum of squares between the group means and dividing it by the degrees of freedom associated with the groups. A higher MSB indicates that the group means are more spread out, suggesting significant differences among the groups.
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Sampling Distribution of Sample Proportion

Variance Within Samples (MSW)

Mean Square Within (MSW) represents the variance within each sample or group. It is calculated by taking the sum of squares of the individual observations from their respective group means and dividing it by the degrees of freedom within the groups. MSW reflects the variability of data points within the same group, indicating how much individual observations differ from their group mean.
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Sampling Distribution of Sample Proportion

Analysis of Variance (ANOVA)

ANOVA is a statistical method used to compare the means of three or more groups to determine if at least one group mean is significantly different from the others. It utilizes both MSB and MSW to calculate the F-ratio, which helps assess the overall significance of the differences among group means. Understanding ANOVA is crucial for interpreting the relationship between MSB and MSW in the context of hypothesis testing.
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Related Practice
Textbook Question

What conditions are necessary in order to use a one-way ANOVA test?

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Textbook Question

Finding Expected Frequencies

In Exercises 3–6, find the expected frequency for the values of n and pᵢ.


n=500, pᵢ=0.9

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Textbook Question

Performing a Chi-Square Goodness-of-Fit Test

In Exercises 7–16, (a) identify the claim and state H₀ and Hₐ, (b) find the critical value and identify the rejection region, (c) find the chi-square test statistic, (d) decide whether to reject or fail to reject the null hypothesis, and (e) interpret the decision in the context of the original claim.


Coffee A researcher claims that the numbers of cups of coffee U.S. adults drink per day are distributed as shown in the figure. You randomly select 1600 U.S. adults and ask them how many cups of coffee they drink per day. The table shows the results. At α=0.05, test the researcher’s claim. (Adapted from Gallup)


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Textbook Question

"In Exercises 13–18, test the claim about the difference between two population variances σ₁² and σ₂² at the level of significance α. Assume the samples are random and independent, and the populations are normally distributed.


Claim: σ₁² > σ₂²; α = 0.10.

Sample statistics: s₁² = 773, n₁ = 5 and s₂² = 765, n₂ = 6"

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Textbook Question

Conditional Relative Frequencies In Exercises 37–42, use the contingency table from Exercises 33–36, and the information below.

Relative frequencies can also be calculated based on the row totals (by dividing each row entry by the row’s total) or the column totals (by dividing each column entry by the column’s total). These frequencies are conditional relative frequencies and can be used to determine whether an association exists between two categories in a contingency table.


What percent of U.S. adults ages 25 and over who have a degree are not in the civilian labor force?

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Textbook Question

Finding Expected Frequencies

In Exercises 3–6, find the expected frequency for the values of n and pᵢ.


n=230, pᵢ=0.25

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