audps: The Area Under the Disease Progress Stairs

In myaseen208/agricolae: Statistical Procedures for Agricultural Research

The Area Under the Disease Progress Stairs

Description

A better estimate of disease progress is the area under the disease progress stairs (AUDPS). The AUDPS approach improves the estimation of disease progress by giving a weight closer to optimal to the first and last observations.

AUDPS. For the illustration one considers three evaluations (14, 21 and 28 days) and percentage of damage in the plant 40, 80 and 90 (interval between dates of evaluation 7 days). AUDPS = 1470. The evaluations can be at different interval. AUDPS= sum( rectangle area by interval in times evaluation ) see example.

Usage

audps(evaluation, dates, type = "absolute")

## Default S3 method:
audps(evaluation, dates, type = "absolute")

Arguments

evaluation	Table of data of the evaluations: Data frame
dates	Vector of dates corresponding to each evaluation
type	relative, absolute

Value

Vector with relative or absolute audps.

Author(s)

1. Felipe de Mendiburu ([e-mail])

2. Muhammad Yaseen ([e-mail])

References

Ivan Simko, and Hans-Peter Piepho, (2012). The area under the disease progress stairs: Calculation, advantage, and application. Phytopathology 102:381- 389.

Examples

library(agricolae)
dates<-c(14,21,28) # days
# example 1: evaluation - vector
evaluation<-c(40,80,90)
audps(evaluation,dates)
audps(evaluation,dates,"relative")
x<-seq(10.5,31.5,7)
y<-c(40,80,90,90)
plot(x,y,"s",ylim=c(0,100),xlim=c(10,32),axes=FALSE,col="red" ,ylab="",xlab="")
title(cex.main=0.8,main="Absolute or Relative AUDPS\nTotal area=(31.5-10.5)*100=2100",
ylab="evaluation",xlab="dates" )
points(x,y,type="h")
z<-c(14,21,28)
points(z,y[-3],col="blue",lty=2,pch=19)
points(z,y[-3],col="blue",lty=2,pch=19)
axis(1,x,pos=0)
axis(2,c(0,40,80,90,100),las=2)
text(dates,evaluation+5,dates,col="blue")
text(14,20,"A = (17.5-10.5)*40",cex=0.8)
text(21,40,"B = (24.5-17.5)*80",cex=0.8)
text(28,60,"C = (31.5-24.5)*90",cex=0.8)
text(14,95,"audps = A+B+C = 1470")
text(14,90,"relative = audps/area = 0.7")
# It calculates audpc absolute
absolute<-audps(evaluation,dates,type="absolute")
print(absolute)
rm(evaluation, dates, absolute)

myaseen208/agricolae documentation built on April 4, 2023, 5:23 a.m.