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Ch. 12 - Analysis of Variance
Triola - Elementary Statistics 14th Edition
Triola14th EditionElementary StatisticsISBN: 9780137366446Not the one you use?Change textbook
Chapter 12, Problem 12.Q.7

One vs. Two What is the fundamental difference between one-way analysis of variance and two-way analysis of variance?

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1
Understand that both one-way and two-way ANOVA are statistical methods used to compare means across groups to see if there are significant differences.
Recognize that one-way ANOVA involves only one independent categorical variable (factor) with two or more levels or groups, and it tests whether the means across these groups differ.
Know that two-way ANOVA involves two independent categorical variables (factors), each with two or more levels, and it tests for the main effects of each factor as well as any interaction effect between the two factors.
Recall that the interaction effect in two-way ANOVA examines whether the effect of one factor depends on the level of the other factor, which is not possible to assess in one-way ANOVA.
Summarize that the fundamental difference lies in the number of factors analyzed: one-way ANOVA analyzes one factor, while two-way ANOVA analyzes two factors and their interaction.

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Key Concepts

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

One-Way Analysis of Variance (ANOVA)

One-way ANOVA is a statistical method used to compare the means of three or more groups based on a single independent factor. It tests whether there are any statistically significant differences among group means by analyzing variance within and between groups.
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Introduction to ANOVA

Two-Way Analysis of Variance (ANOVA)

Two-way ANOVA extends one-way ANOVA by examining the effect of two independent factors simultaneously on a dependent variable. It also evaluates the interaction effect between the two factors, showing how the combination of factors influences the outcome.
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Introduction to ANOVA

Interaction Effect in Two-Way ANOVA

The interaction effect occurs when the impact of one independent factor on the dependent variable depends on the level of the other factor. Identifying interaction helps understand if factors work independently or jointly affect the response variable.
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Related Practice
Textbook Question

Birth Weights The table below lists some of the same data used in the preceding exercise, but the seven days of the week are combined into weekday (Monday, Tuesday, Wednesday, Thursday, Friday) and weekend days (Saturday, Sunday). Also, the birth weights are converted to kilograms. What do you conclude?

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Textbook Question

Pulse Rates Shown below are pulse rates from Data Set 1 “Body Data” in Appendix B, and the StatCrunch display from two-way analysis of variance of these data. In analyzing these data, what important feature is addressed with two-way analysis of variance that is not addressed with two separate tests of (1) difference between mean pulse rates based on gender, or (2) differences among the mean pulse rates in the different age brackets?

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Textbook Question

Interaction

b. If there does appear to be an interaction between gender and age bracket, how should we continue with the procedure for two-way analysis of variance?

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Textbook Question

Birth Weights Data Set 6 “Births” includes birth weights (g), hospitals, and the day of the week that mothers were admitted to the hospital. Using rows to represent the four hospitals (Albany Medical Center, Bellevue Hospital Center, Olean General Hospital, Strong Memorial Hospital), and using columns to represent the seven different days of the week, a two-way table has 28 individual cells. Using five birth weights for each of those 28 cells and using StatCrunch for two-way analysis of variance, we get the results displayed below. What do you conclude?

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Textbook Question

Gender and Age Bracket Based on the display included with Exercise 8, what are the final conclusions?

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Textbook Question

"Interaction

a. Based on the display included with the preceding exercise, what do you conclude about an interaction between gender and age bracket?

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