SP: Understanding Strength of Paper with a Three Factorial...

In ACSWR: A Companion Package for the Book "A Course in Statistics with R"

Description

The strength of a paper depends on three variables: (i) the percentage of hardwood concentration in the raw pulp, (ii) the vat pressure, and (iii) the cooking time of the pulp. The hardwood concentration is tested at three levels of 2, 4, and 8 percentage, the vat pressure at 400, 500, and 650, while the cooking time is at 3 and 4 hours. For each combination of the these three factor variables, 2 observations are available, and thus a total of 3.3.2.2 = 36 observations. The goal of the study is investigation of the impact of the three factor variables on the strength of the paper, and the presence of interaction effect, if any.

Usage

data(SP)

Format

A data frame with 36 observations on the following 4 variables.

Hardwood

a factor with levels 2 4 8

Pressure

a factor with levels 400 500 650

Cooking_Time

a factor with levels 3 4

Strength

a numeric vector

References

Montgomery, D. C. (1976-2012). Design and Analysis of Experiments, 8e. J.Wiley.

Examples

data(SP)
summary(SP.aov <- aov(Strength~.^3,SP))

Example output

                               Df Sum Sq Mean Sq F value   Pr(>F)    
Hardwood                        2  3.764   1.882   2.458 0.113792    
Pressure                        2 24.041  12.020  15.701 0.000113 ***
Cooking_Time                    1 14.694  14.694  19.194 0.000360 ***
Hardwood:Pressure               4 14.224   3.556   4.645 0.009422 ** 
Hardwood:Cooking_Time           2  0.304   0.152   0.198 0.821750    
Pressure:Cooking_Time           2  4.951   2.475   3.233 0.063137 .  
Hardwood:Pressure:Cooking_Time  4  1.751   0.438   0.572 0.686497    
Residuals                      18 13.780   0.766                     
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Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

ACSWR documentation built on May 2, 2019, 6:53 a.m.