drc (version 1.3-0)

PestSci: Inhibition of photosynthesis

Description

Inhibition of photosynthesis in response to two synthetic photosystem II inhibitors, the herbicides diuron and bentazone. The effect of oxygen consumption of thylakoid membranes (Chloroplasts) from Spinach was measured after incubation with the synthetic inhibitors, resulting in 5 dose-response curves.

Usage

data(PestSci)

source

Streibig, J. C. (1998) Joint action of natural and synthetic photosystem II inhibitors, Pesticide Science, 55, 137--146.

Details

CURVE denotes a total of five independent assays with two herbicides. HERBICIDE denotes the names of the herbicides. DOSE is the concentration of the herbicides muMol and SLOPE is the oxygen consumption of thylakoid membranes.

Examples

PestSci[1:5,]  # displaying first 5 rows in the data set
str(PestSci)   # compactly displaying the structure of the PestSci object

## Analysis accounting for variance heterogeneity 
##  using Box-Cox-transformation
model1 <- multdrc(SLOPE~DOSE, CURVE, data=PestSci, boxcox=TRUE)
summary(model1)  
## note: some estimates have indeterminate estimated standard error

model2 <- multdrc(SLOPE~DOSE, CURVE, data=PestSci, boxcox=TRUE,
control=mdControl(bcAdd=0.05))
summary(model2)  
## note: now all estimates have estimated standard errors

## Analysis accounting for variance heterogeneity using variance modelling
model3 <- multdrc(SLOPE~DOSE, CURVE, data=PestSci, varPower=TRUE)
summary(model3)

## The same model in specified in 4 ways (first 3 with same parameterisation)
model4 <- multdrc(SLOPE~DOSE, CURVE, data=PestSci)

model5 <- multdrc(SLOPE~DOSE, CURVE, data=PestSci, collapse=data.frame(CURVE,CURVE,CURVE,CURVE))

model6 <- multdrc(SLOPE~DOSE, CURVE, data=PestSci, 
collapse=list(~factor(CURVE)-1,~factor(CURVE)-1,~factor(CURVE)-1,~factor(CURVE)-1))

model7 <- multdrc(SLOPE~DOSE, CURVE, data=PestSci, 
collapse=list(~factor(CURVE),~factor(CURVE),~factor(CURVE),~factor(CURVE)))

## Example using 'hetvar' argument 
##  for heterogeneous variances
model8 <- multdrc(SLOPE~DOSE, CURVE, data = PestSci, 
hetvar = HERBICIDE, boxcox = TRUE, bcAdd = 0.01)
summary(model8)

rm(model1, model2, model3, model4, model5, model6, model7, model8)