Figure 7. Proportion of structural variance (PSV) (C/(C_o + C), where C = sill value-nugget variance, and C_o = nugget variance) displayed over time for spherical variogram models based on geostatistical analysis of dollar spot epidemics on a mixed sward of creeping bentgrass and annual bluegrass from 2000 to 2002. Dotted lines in the plot area represent the area where structural variance accounted for between 30 and 60% of the total variation present.