cochran.latin.Rd
Six wheat plots were sampled by six operators and shoot heights measured. The operators sampled plots in six ordered sequences. The dependent variate was the difference between measured height and true height of the plot.
A data frame with 36 observations on the following 4 variables.
row
row
col
column
operator
operator factor
diff
difference between measured height and true height
Cochran, W.G. and Cox, G.M. (1957), Experimental Designs, 2nd ed., Wiley and Sons, New York.
library(agridat) data(cochran.latin) dat <- cochran.latin libs(desplot) desplot(dat, diff~col*row, text=operator, cex=1, # aspect unknown main="cochran.latin")dat <- transform(dat, rf=factor(row), cf=factor(col)) aov.dat <- aov(diff ~ operator + Error(rf*cf), dat) summary(aov.dat)#> #> Error: rf #> Df Sum Sq Mean Sq F value Pr(>F) #> Residuals 5 28.6 5.72 #> #> Error: cf #> Df Sum Sq Mean Sq F value Pr(>F) #> Residuals 5 78.87 15.77 #> #> Error: rf:cf #> Df Sum Sq Mean Sq F value Pr(>F) #> operator 5 155.60 31.119 9.35 0.000103 *** #> Residuals 20 66.56 3.328 #> --- #> Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1#> Tables of means #> Grand mean #> #> 4.758333 #> #> operator #> operator #> a b c d e f #> 6.067 5.583 6.117 6.917 2.667 1.200