agridat (version 1.8.1)

bridges.cucumber: Cucumber yields in Latin Square design.

Description

Cucumber yields in Latin Square design at two locs.

source

William Bridges, 1989. Analysis of a plant breeding experiment with heterogeneous variances using mixed model equations. Applications of mixed models in agriculture and related disciplines, S. Coop. Ser. Bull, 45--51. Used with permission of William Bridges.

Details

Conducted at Clemson University in 1985. four cucumber cultivars were grown in a Latin Square design at Clemson, SC, and Tifton, GA.

Examples

dat <- bridges.cucumber
dat <- transform(dat, rowf=factor(row), colf=factor(col))

desplot(yield~col*row|loc, data=dat, text=gen, cex=1,
        main="bridges.cucumber")

require(asreml)
## Random row/col/resid. Same as Bridges 1989, p. 147
m1 <- asreml(yield ~ 1 + gen + loc + loc:gen,
             random = ~ rowf:loc + colf:loc, data=dat)
summary(m1)$varcomp
##            Effect Estimate Std Err Z Ratio Con
## rowf:loc!rowf.var    31.62   23.02     1.4 Pos
##  loc:colf!loc.var    18.08   15.32     1.2 Pos
##        R!variance    31.48   12.85     2.4 Pos

## Random row/col/resid at each loc. Matches p. 147
m2 <- asreml(yield ~ 1 + gen + loc + loc:gen,
             random = ~ at(loc):rowf + at(loc):colf, data=dat,
             rcov = ~at(loc):units)
summary(m2)$varcomp
##                         Effect Estimate Std Err Z Ratio Con
## at(loc, Clemson):rowf!rowf.var    32.32  36.58     0.88 Pos
##  at(loc, Tifton):rowf!rowf.var    30.92  28.63     1.1  Pos
## at(loc, Clemson):colf!colf.var    22.55  28.78     0.78 Pos
##  at(loc, Tifton):colf!colf.var    13.62  14.59     0.93 Pos
##           loc_Clemson!variance    46.85  27.05     1.7  Pos
##            loc_Tifton!variance    16.11   9.299    1.7  Pos

predict(m2, classify='loc:gen')$predictions$pvals
##     loc      gen Predicted Std Err    Status
## Clemson   Dasher     45.55   5.043 Estimable
## Clemson Guardian     31.62   5.043 Estimable
## Clemson Poinsett     21.42   5.043 Estimable
## Clemson   Sprint     25.95   5.043 Estimable
##  Tifton   Dasher     50.48   3.894 Estimable
##  Tifton Guardian     38.72   3.894 Estimable
##  Tifton Poinsett     33.01   3.894 Estimable
##  Tifton   Sprint     39.18   3.894 Estimable