One Way ANOVA

H0: Mu1 = Mu2 = Mu3

Syntax

aov(formula, data = name.data) Example

aov(Y~X, data = name.data)

x=c(4,2,3,1,2)
y=c(4,5,1,3)
z=c(1,2,4,5,1,1,1)
Y=c(x,y,z)
X=c(rep("x",5),rep("y",4),rep("z",7))
aov(Y~X)
## Call:
##    aov(formula = Y ~ X)
## 
## Terms:
##                         X Residuals
## Sum of Squares   3.192857 30.807143
## Deg. of Freedom         2        13
## 
## Residual standard error: 1.539409
## Estimated effects may be unbalanced
summary(aov(Y~X))
##             Df Sum Sq Mean Sq F value Pr(>F)
## X            2  3.193   1.596   0.674  0.527
## Residuals   13 30.807   2.370

One Way ANOVA

H0: Mu1 = Mu2 = Mu3

Syntax

aov(formula, data = name.data)

Example

aov(Y~X, data = name.data)

Equal observations (in each cell)

x=c(14,9,3,7,2)
y=c(4,5,1,3,4)
z=c(1,1,1,1,1)
Y=c(x,y,z)
X=c(rep("x",5),rep("y",5),rep("z",5))
aov(Y~X)
## Call:
##    aov(formula = Y ~ X)
## 
## Terms:
##                     X Residuals
## Sum of Squares   91.2     103.2
## Deg. of Freedom     2        12
## 
## Residual standard error: 2.932576
## Estimated effects may be unbalanced
summary(aov(Y~X))
##             Df Sum Sq Mean Sq F value Pr(>F)  
## X            2   91.2    45.6   5.302 0.0224 *
## Residuals   12  103.2     8.6                 
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Two Way ANOVA

H0: Mu1 = Mu2 = Mu3 H0: beta1 = beta2 = beta3 = beta4 = beta5

Syntax

aov(formula, data = name.data)

x=c(14,9,3,7,2)
y=c(4,5,1,3,4)
z=c(1,1,1,1,1)

Y=c(x,y,z)

X=c(rep("x",5),rep("y",5),rep("z",5))
Z=rep(LETTERS[1:5],3)
cbind(Y,X,Z)
##       Y    X   Z  
##  [1,] "14" "x" "A"
##  [2,] "9"  "x" "B"
##  [3,] "3"  "x" "C"
##  [4,] "7"  "x" "D"
##  [5,] "2"  "x" "E"
##  [6,] "4"  "y" "A"
##  [7,] "5"  "y" "B"
##  [8,] "1"  "y" "C"
##  [9,] "3"  "y" "D"
## [10,] "4"  "y" "E"
## [11,] "1"  "z" "A"
## [12,] "1"  "z" "B"
## [13,] "1"  "z" "C"
## [14,] "1"  "z" "D"
## [15,] "1"  "z" "E"
aov(Y~X+Z)
## Call:
##    aov(formula = Y ~ X + Z)
## 
## Terms:
##                        X        Z Residuals
## Sum of Squares  91.20000 43.73333  59.46667
## Deg. of Freedom        2        4         8
## 
## Residual standard error: 2.726414
## Estimated effects may be unbalanced
summary(aov(Y~X+Z))
##             Df Sum Sq Mean Sq F value Pr(>F)  
## X            2  91.20   45.60   6.135 0.0243 *
## Z            4  43.73   10.93   1.471 0.2971  
## Residuals    8  59.47    7.43                 
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1