131
In Fig. 11.3, we show the results of a Plackett-Luce tree, applied on data with a
covariate representing seasonal rainfall. The Plackett-Luce tree determines how to
use the drought variable to split the data.
In real analyses, we derive covariates from a geospatial weather dataset, using
the GPS point of each farm and the planting date to retrieve data from the right place
4.0
4.5
5.0
5.5
6.0
6 .5
7.0
7 .5
0
1
2
3
4
Mean v alue from simulation
Log−odds of winning from Variety 1
r= 0.994
Var1
Var2
Var3
Var4
Var5
Var6
Var7
Var8
Var9
Var10
Var11
Var12 Var13
Var14
Var15
Var16
Var17 Var18
Var19 Var20
Fig. 11.2 Results of Example 1. Relation between simulation input values and Plackett-Luce
output values. Based on a simulation of 500 farmers, each ranking 3 varieties out of a set of 20
Fig. 11.3 Results of Example 2. Half of the farmers were selecting under a drought condition, in
which Varieties 6 and 10 excelled. The Plackett-Luce tree distinguishes correctly between the two
groups
11 Generating Farm-Validated Variety Recommendations for Climate Adaptation