arbovirus

Data from a dose-response experiment with an arbovirus involving two treatment groups (FP and SP). For each dose level, the total number of subjects and the numbers of dead and defective subjects were recorded.

Usage

data(arbovirus)

Format

A data frame with 9 observations on the following 5 variables.

dose

a numeric vector

total

a numeric vector

dead

a numeric vector

def

a numeric vector

trt

a categorical vector

Examples

library(drc)

## Displaying the data
head(arbovirus)
#>   dose total dead def trt
#> 1    3    17    3   1  FP
#> 2   18    19    4   1  FP
#> 3   30    19    8   2  FP
#> 4   90    20   17   1  FP
#> 5    3    19    1   0   T
#> 6   20    19    2   0   T

## Fitting a two-parameter log-logistic model for binomial response
arbovirus.m1 <- drm(dead/total ~ dose, trt, weights = total,
data = arbovirus, fct = LL.2(), type = "binomial")
summary(arbovirus.m1)
#> 
#> Model fitted: Log-logistic (ED50 as parameter) with lower limit at 0 and upper limit at 1 (2 parms)
#> 
#> Parameter estimates:
#> 
#>         Estimate  Std. Error t-value   p-value    
#> b:FP -1.0219e+00  2.8425e-01 -3.5949 0.0003245 ***
#> b:T  -2.8993e-01  7.1182e-02 -4.0731 4.638e-05 ***
#> e:FP  3.2617e+01  8.6014e+00  3.7921 0.0001494 ***
#> e:T   4.1896e+04  3.6484e+04  1.1483 0.2508315    
#> ---
#> Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

## Plotting the fitted curves
plot(arbovirus.m1, xlab = "Dose", ylab = "Proportion dead")