1. Analysis of Variance Objective
Compute and interpret the results of a one-way ANOVA.
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2. Introduction
Most experiments involves a study of the effect of one or more variables on a response.
A response can be affected by two types of independent variables:
Quantitative
Qualitative
These independent variables that can be controlled in an experiment are called factors
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3. Factors - Level - Blocks - Treatment
To show that:
In study of the wear for three types of tires A, B, and C, on each of four automobiles, “tire types” is a factor representing a single quantitative variable at three levels.
Automobiles are blocks representing a single quantitative variable at four levels
Response depends on the factors that represent treatments
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4. Analysis of Variance: Assumptions
Observations are drawn from normally distributed populations. Observations represent random samples from the populations. Variances of the populations are equal.
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5. Partitioning Total Sum of Squares of Variation
SST
(Total Sum of Squares)
SSTr
(Treatment Sum of Squares)
SSE
(Error Sum of Squares)
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6. One-Way ANOVA: Sums of Squares Definitions
Sum of squares of treatments SSTr:
Sum of squares of error SSE:
Total sum of squares SST:
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7. Cont …
Total sum of squares = Treatments sum of squares + Error sum of squares
SST = SSTr + SSE
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11. One-Way ANOVA: Computational Formulas
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12. One-Way ANOVA: Procedural Overview
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13. EX: Valve Openings by Operator1 2 3 4
6.33
6.26
6.44
6.29
6.36
6.38
6.23
6.31
6.58
6.19
6.27
6.54
6.21
6.4
6.56
6.5
6.34
6.22
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14. One-Way ANOVA: Preliminary Calculations1 2 3 4
6.33
6.26
6.44
6.29
6.36
6.38
6.23
6.31
6.58
6.19
6.27
6.54
6.21
6.4
6.56
6.5
6.34
6.22 Tj
T1 = 31.59
T2 = 50.22
T3 = 45.42
T4 = 24.92
T = nj
n1 = 5
n2 = 8
n3 = 7
n4 = 4
N = 24
Mean
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15. One-Way ANOVA: Sum of Squares Calculations
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16. One-Way ANOVA: Sum of Squares Calculations
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17. One-Way ANOVA: Mean Square and F Calculations
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18. Analysis of Variance for Valve Openings
Source of Variations df SS MS F
Between Tr
Error
Total
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19. A Portion of the F Table for  = 0.05
df1
df 2 1 2 3 4 5 6 7 8 9
161.45
199.50
215.71
224.58
230.16
233.99
236.77
238.88
240.54 … 18
4.41
3.55
3.16
2.93
2.77
2.66
2.58
2.51
2.46 19
4.38
3.52
3.13
2.90
2.74
2.63
2.54
2.48
2.42 20
4.35
3.49
3.10
2.87
2.71
2.60
2.45
2.39 21
4.32
3.47
3.07
2.84
2.68
2.57
2.49
2.37
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20. One-Way ANOVA: Procedural Summary
Rejection Region

Critical Value
Non rejection
Region
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21. Output for the Valve Opening Example from Excel
Anova: Single Factor
SUMMARY
Groups
Count
Sum
Average
Variance
Operator 1 5
31.59
6.318
Operator 2 8
50.22
6.2775
Operator 3 7
45.42
Operator 4 4
24.92
6.23
ANOVA
Source of Variation SS df MS F
P-value
F crit
Between Groups 3
Within Groups 20
Total 23
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22. One-Way Analysis of Variance using Minitab
Source DF SS MS F P
Factor
Error
Total
Individual 95% CIs For Mean
Based on Pooled StDev
Level N Mean StDev
O (-----*------)
O (----*-----)
O (-----*----)
O (------* )
Pooled StDev =
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23. HW
The reaction times for two different stimuli in a psychological word association experiment were compared by using each stimulus on independent random samples of size eight. Thus a total of sixteen people were used in the experiment. Do the following data present sufficient evidence to indicate that there is a difference in the mean reaction times for the two stimulus?
Stimulus 1:
Stimulus 2:
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24. Dr. Ahmed M. Sultan