Math Problem Statement

Everybody has taste preferences. Most people claim to be able to tell the difference between "their" brand and other non-preferred brands. Suppose you put your taste buds to the test to see whether you can taste the difference between various brands of ice cream. Ice Cream is usually sold as store-brand, premium, or super-premium, and the difference is supposed to be the quality of the ingredients. You buy several gallons of chocolate ice cream, place small scoops into plain paper cups, and then ask three different groups of people to rate the tastes of the ice cream using an interval rating scale from 1 (bad) to 7 (great). The summary of the results are in the table below. Use this data to answer questions 1-5 below.

Store-Brand Premium Super-Premium 7 3 5 4 2 7 5 6 3 2 5 5 3 6 2 What is the Sum of Squares Between Groups?

Group of answer choices

1.904

2.451

23.015

0.133

17.897

Solution

To find the Sum of Squares Between Groups (SSB), we can follow these steps:

Step 1: Calculate the Mean of Each Group

  • Store-Brand Group: 7, 4, 5, 2, 3 MeanStore-Brand=7+4+5+2+35=215=4.2\text{Mean}_{\text{Store-Brand}} = \frac{7 + 4 + 5 + 2 + 3}{5} = \frac{21}{5} = 4.2

  • Premium Group: 3, 2, 6, 5, 6 MeanPremium=3+2+6+5+65=225=4.4\text{Mean}_{\text{Premium}} = \frac{3 + 2 + 6 + 5 + 6}{5} = \frac{22}{5} = 4.4

  • Super-Premium Group: 5, 7, 3, 5, 2 MeanSuper-Premium=5+7+3+5+25=225=4.4\text{Mean}_{\text{Super-Premium}} = \frac{5 + 7 + 3 + 5 + 2}{5} = \frac{22}{5} = 4.4

Step 2: Calculate the Grand Mean

This is the overall mean of all the values, combining all groups:

Grand Mean=(7+4+5+2+3)+(3+2+6+5+6)+(5+7+3+5+2)15\text{Grand Mean} = \frac{(7 + 4 + 5 + 2 + 3) + (3 + 2 + 6 + 5 + 6) + (5 + 7 + 3 + 5 + 2)}{15} Grand Mean=21+22+2215=6515=4.33\text{Grand Mean} = \frac{21 + 22 + 22}{15} = \frac{65}{15} = 4.33

Step 3: Calculate the Sum of Squares Between Groups (SSB)

SSB=n1(MeanStore-BrandGrand Mean)2+n2(MeanPremiumGrand Mean)2+n3(MeanSuper-PremiumGrand Mean)2SSB = n_1 (\text{Mean}_{\text{Store-Brand}} - \text{Grand Mean})^2 + n_2 (\text{Mean}_{\text{Premium}} - \text{Grand Mean})^2 + n_3 (\text{Mean}_{\text{Super-Premium}} - \text{Grand Mean})^2

Where n1n_1, n2n_2, and n3n_3 are the number of observations in each group (which is 5 for each group).

Substitute the values into the formula:

SSB=5(4.24.33)2+5(4.44.33)2+5(4.44.33)2SSB = 5 \left(4.2 - 4.33\right)^2 + 5 \left(4.4 - 4.33\right)^2 + 5 \left(4.4 - 4.33\right)^2

SSB=5(0.13)2+5(0.07)2+5(0.07)2SSB = 5 \left( -0.13 \right)^2 + 5 \left( 0.07 \right)^2 + 5 \left( 0.07 \right)^2

SSB=5×(0.0169)+5×(0.0049)+5×(0.0049)SSB = 5 \times (0.0169) + 5 \times (0.0049) + 5 \times (0.0049)

SSB=0.0845+0.0245+0.0245=0.1335SSB = 0.0845 + 0.0245 + 0.0245 = 0.1335

Step 4: Round the Result

SSB0.133SSB \approx 0.133

Thus, the Sum of Squares Between Groups is approximately 0.133.

The correct answer is 0.133.

Would you like more details or clarification on this process?

Here are 5 follow-up questions you might find interesting:

  1. What is the Sum of Squares Within Groups (SSW)?
  2. How do you calculate the F-statistic for this data?
  3. What does the Sum of Squares Between Groups tell you about the data?
  4. How would you interpret the significance of the F-statistic in an ANOVA test for this data?
  5. What is the formula for calculating the degrees of freedom in an ANOVA?

Tip: In ANOVA, the sum of squares between groups (SSB) represents the variability between the group means, and the sum of squares within groups (SSW) represents the variability within each group. Together, they help assess if the group means are significantly different.

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Math Problem Analysis

Mathematical Concepts

Statistics
ANOVA
Sum of Squares Between Groups

Formulas

SSB = n1 * (Mean_Store-Brand - Grand Mean)^2 + n2 * (Mean_Premium - Grand Mean)^2 + n3 * (Mean_Super-Premium - Grand Mean)^2

Theorems

Sum of Squares Between Groups in ANOVA

Suitable Grade Level

Grades 11-12