Barley

Data from a dose-response experiment measuring the weight of barley (Hordeum vulgare) at different dose levels of a substance.

Usage

data(barley)

Format

A data frame with 18 observations of the following 2 variables.

Dose

a numeric vector

weight

a numeric vector

Examples

library(drc)

## Displaying the data
head(barley)
#>       Dose weight
#> 1  0.00000   57.2
#> 2  0.00000   49.8
#> 3 21.09375   62.2
#> 4 21.09375   30.6
#> 5 42.18750   40.9
#> 6 42.18750   70.9

## Fitting a four-parameter log-logistic model
barley.m1 <- drm(weight ~ Dose, data = barley, fct = LL.4())
summary(barley.m1)
#> 
#> Model fitted: Log-logistic (ED50 as parameter) (4 parms)
#> 
#> Parameter estimates:
#> 
#>               Estimate Std. Error t-value   p-value    
#> b:(Intercept)   9.7084    42.9166  0.2262   0.82430    
#> c:(Intercept)  11.1275     3.7803  2.9435   0.01068 *  
#> d:(Intercept)  52.0478     3.2487 16.0212 2.123e-10 ***
#> e:(Intercept) 286.2600   209.6374  1.3655   0.19364    
#> ---
#> Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
#> 
#> Residual standard error:
#> 
#>  9.241941 (14 degrees of freedom)

## Plotting the fitted curve
plot(barley.m1, xlab = "Dose", ylab = "Weight")