Problem 1 :

a) Model Equation for a full 2^3 factorial model: \[ y_{ijkl} = \mu + \alpha_{i} + \beta_{j} + \gamma _{k}+\alpha \beta _{ij} + \beta \gamma _{jk} +\alpha \gamma _{ik} +\alpha \beta \gamma _{ijk}+ \varepsilon _{ijkl} \]

b) What factors are deemed significant

data <- read.csv ("https://raw.githubusercontent.com/tmatis12/datafiles/main/PowderProduction.csv")
data
##    Ammonium StirRate Temperature Density
## 1         2      100           8   14.68
## 2         2      100           8   15.18
## 3        30      100           8   15.12
## 4        30      100           8   17.48
## 5         2      150           8    7.54
## 6         2      150           8    6.66
## 7        30      150           8   12.46
## 8        30      150           8   12.62
## 9         2      100          40   10.95
## 10        2      100          40   17.68
## 11       30      100          40   12.65
## 12       30      100          40   15.96
## 13        2      150          40    8.03
## 14        2      150          40    8.84
## 15       30      150          40   14.96
## 16       30      150          40   14.96
library (GAD)
data$Ammonium <- as.fixed(data$Ammonium)
data$StirRate <- as.fixed(data$StirRate)
data$Temperature <- as.fixed(data$Temperature)

model <- aov (data$Density~ data$Ammonium + data$StirRate + data$Temperature +  data$Ammonium*data$StirRate + data$StirRate*data$Temperature + data$Ammonium*data$Temperature + data$Ammonium*data$StirRate*data$Temperature)
summary(model)
##                                              Df Sum Sq Mean Sq F value  Pr(>F)
## data$Ammonium                                 1  44.39   44.39  11.180 0.01018
## data$StirRate                                 1  70.69   70.69  17.804 0.00292
## data$Temperature                              1   0.33    0.33   0.083 0.78117
## data$Ammonium:data$StirRate                   1  28.12   28.12   7.082 0.02875
## data$StirRate:data$Temperature                1  10.13   10.13   2.551 0.14889
## data$Ammonium:data$Temperature                1   0.02    0.02   0.005 0.94281
## data$Ammonium:data$StirRate:data$Temperature  1   1.52    1.52   0.383 0.55341
## Residuals                                     8  31.76    3.97                
##                                                
## data$Ammonium                                * 
## data$StirRate                                **
## data$Temperature                               
## data$Ammonium:data$StirRate                  * 
## data$StirRate:data$Temperature                 
## data$Ammonium:data$Temperature                 
## data$Ammonium:data$StirRate:data$Temperature   
## Residuals                                      
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Comments : As the interaction p value is 0.5534 is greater than 0.05 we fail to reject null hypothesis.

model1 <- aov (data$Density~ data$Ammonium + data$StirRate + data$Temperature +  data$Ammonium*data$StirRate + data$StirRate*data$Temperature + data$Ammonium*data$Temperature)
summary(model1)
##                                Df Sum Sq Mean Sq F value  Pr(>F)   
## data$Ammonium                   1  44.39   44.39  12.004 0.00711 **
## data$StirRate                   1  70.69   70.69  19.115 0.00179 **
## data$Temperature                1   0.33    0.33   0.089 0.77268   
## data$Ammonium:data$StirRate     1  28.12   28.12   7.603 0.02221 * 
## data$StirRate:data$Temperature  1  10.13   10.13   2.739 0.13232   
## data$Ammonium:data$Temperature  1   0.02    0.02   0.006 0.94054   
## Residuals                       9  33.28    3.70                   
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Comments : As the interaction p value is 0.94054 is greater than 0.05 we fail to reject null hypothesis and claim there is no three factor interaction

model2 <- aov (data$Density~ data$Ammonium + data$StirRate + data$Temperature +  data$Ammonium*data$StirRate + data$StirRate*data$Temperature)
summary(model2)
##                                Df Sum Sq Mean Sq F value  Pr(>F)    
## data$Ammonium                   1  44.39   44.39  13.329 0.00446 ** 
## data$StirRate                   1  70.69   70.69  21.225 0.00097 ***
## data$Temperature                1   0.33    0.33   0.098 0.76019    
## data$Ammonium:data$StirRate     1  28.12   28.12   8.443 0.01568 *  
## data$StirRate:data$Temperature  1  10.13   10.13   3.041 0.11178    
## Residuals                      10  33.30    3.33                    
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Comment : As interaction p value is 0.11178 is greater than 0.05 we fail to reject null hyptohesis and claim there is no three factor interaction

model3 <- aov (data$Density~ data$Ammonium + data$StirRate + data$Temperature +  data$Ammonium*data$StirRate)
summary(model3)
##                             Df Sum Sq Mean Sq F value  Pr(>F)   
## data$Ammonium                1  44.39   44.39  11.242 0.00644 **
## data$StirRate                1  70.69   70.69  17.903 0.00141 **
## data$Temperature             1   0.33    0.33   0.083 0.77861   
## data$Ammonium:data$StirRate  1  28.12   28.12   7.121 0.02185 * 
## Residuals                   11  43.43    3.95                   
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Comment : As interaction p value is 0.02185 is less than 0.05 we reject null hypothesis and claim there is significant interaction between Ammonium and Stir rate.

interaction.plot (data$StirRate ,data$Ammonium ,data$Density,col=c("blue","red"))

From the interraction plot , since the lines are not parallel , so we can tell that the interaction between ammonium and StirRate is significant.

Problem 2 :

library(agricolae)
## Warning: package 'agricolae' was built under R version 4.5.2
A<- c("A1","A2")
B<- c("B1","B2")
C <-c("C1","C2")
factors <- c(2,2,2)
design <- design.ab(factors, r = 3, design = "rcbd", seed = 12345)
design$book$A <- factor(design$book$A,labels = A)
design$book$B <- factor(design$book$B,labels =B)
design$book$C <- factor(design$book$C,labels = C)
design$book
##    plots block  A  B  C
## 1    101     1 A2 B2 C1
## 2    102     1 A1 B2 C2
## 3    103     1 A2 B1 C2
## 4    104     1 A1 B1 C2
## 5    105     1 A2 B1 C1
## 6    106     1 A1 B2 C1
## 7    107     1 A2 B2 C2
## 8    108     1 A1 B1 C1
## 9    109     2 A1 B1 C2
## 10   110     2 A2 B2 C2
## 11   111     2 A1 B2 C1
## 12   112     2 A1 B2 C2
## 13   113     2 A1 B1 C1
## 14   114     2 A2 B1 C2
## 15   115     2 A2 B2 C1
## 16   116     2 A2 B1 C1
## 17   117     3 A2 B1 C2
## 18   118     3 A2 B2 C2
## 19   119     3 A2 B2 C1
## 20   120     3 A1 B2 C1
## 21   121     3 A2 B1 C1
## 22   122     3 A1 B2 C2
## 23   123     3 A1 B1 C1
## 24   124     3 A1 B1 C2

Source Code :

data <- read.csv ("https://raw.githubusercontent.com/tmatis12/datafiles/main/PowderProduction.csv")
data

data$Ammonium <- as.fixed(data$Ammonium)
data$StirRate <- as.fixed(data$StirRate)
data$Temperature <- as.fixed(data$Temperature)
library (GAD)
model <- aov (data$Density~ data$Ammonium + data$StirRate + data$Temperature +  data$Ammonium*data$StirRate + data$StirRate*data$Temperature + data$Ammonium*data$Temperature + data$Ammonium*data$StirRate*data$Temperature)
summary(model)

model1 <- aov (data$Density~ data$Ammonium + data$StirRate + data$Temperature +  data$Ammonium*data$StirRate + data$StirRate*data$Temperature + data$Ammonium*data$Temperature)
summary(model1)

model2 <- aov (data$Density~ data$Ammonium + data$StirRate + data$Temperature +  data$Ammonium*data$StirRate + data$StirRate*data$Temperature)
summary(model2)

model3 <- aov (data$Density~ data$Ammonium + data$StirRate + data$Temperature +  data$Ammonium*data$StirRate)
summary(model3)

interaction.plot (data$StirRate ,data$Ammonium ,data$Density,col=c("blue","red"))
library(agricolae)
factors <- c(2,2,2)
design <- design.ab(factors, r = 3, design = "rcbd", seed = 12345)
design$book$A <- factor(design$book$A,levels = 1:2,labels = c("A1", "A2"))
design$book$B <- factor(design$book$B,levels = 1:2,labels = c("B1", "B2"))
design$book$C <- factor(design$book$C,levels = 1:2,labels = c("C1", "C2"))
design$book