. Across site years, the
SCMZ technique had higher areal agreement percentages
in two out of the three site years when compared
with the YBMZ technique. Areal agreement was 37, 41,
and 45% for the SCMZ technique and 24, 38, and 48%
for the YBMZ. The kappa statistic is a measure of how
well a classification is compared with a completely random
classification. As stated above, the kappa statistic is
a more robust statistic for assessing agreement between
two classifications. According to Table 2 (Landis and
Koch, 1977), both SCMZ and YBMZ have “slight agreement”
with yield clusters, indicating that both techniques
are deficient at completely characterizing the
inherent spatial variability in productivity potential
across the fields used in this study. The guidelines of
Landis and Koch (1977; Table 2) indicate that the kappa
statistics were higher for the SCMZ technique across all
site years, suggesting that the SCMZ technique is
relatively better than the YBMZ technique