An Application of Space-Time Analysis to Improve the Epidemiological Understanding of the Papaya-Papaya Yellow Crinkle Pathosystem

Fig. 5. Summary plots for the space-time point pattern analysis for sweet potato little leaf V4 (SPLL-V4).  Time was defined as the month in which a plant was found to be symptomatic and infected by SPLL-V4.  The Data map (A) represents the observed locations of SPLL-V4-infected papaya within the papaya plantation.  The Dzero plot (B) is a perspective plot that examines the difference between the space-time K function and the product of the space and time K functions and is written as:


D0 =K(s,t) - K(s)K(t)              [4]
K(s)K(t)



The Residual Plot (C) is a plot of standardized residuals against the product of the space and time K functions.  This plot is similar to a residual plot from regression analysis and values ±2 are indicative of a space-time interaction occurring.  Finally, the MC results (D) summarizes all of the test statistics from a Monte Carlo simulation, whereby, the time data for each SPLL-V4-infected location was randomly assigned to the fixed locations for SPLL-V4-infected papaya.



Image from Plant Health Progress article:
An Application of Space-Time Analysis to Improve the Epidemiological Understanding of the Papaya-Papaya Yellow Crinkle Pathosystem