Weight change in rats after exposure to a medical drug

For each of 4 dose levels the weight change over 6 monts is reported for 14 rats exposed to an antituberculosis drug, aconiazide.

Usage

data(aconiazide)

Format

A data frame with 55 observations of the following 2 variables.

dose: a numeric vector
weightChange: a numeric vector giving weight change (g) after 6 months of exposure

Source

Beland, F. A. and Dooley, K. L. and Hansen, E. B. and Sheldon, W. G. (1995). Six-month toxicity comparison of the antituberculosis drugs aconiazide and isoniazid in fischer 344 rats. Journal of the American College of Toxicology, 14(4):328–342.

Examples

library(drc)

## Displaying the data
head(aconiazide)
#>   weightChange dose
#> 1        366.0    0
#> 2        326.6    0
#> 3        355.0    0
#> 4        353.8    0
#> 5        354.4    0
#> 6        349.8    0

## Fitting a four-parameter log-logistic model
aconiazide.m1 <- drm(weightChange ~ dose, data = aconiazide, fct = LL.4())
summary(aconiazide.m1)
#> 
#> Model fitted: Log-logistic (ED50 as parameter) (4 parms)
#> 
#> Parameter estimates:
#> 
#>                 Estimate Std. Error t-value p-value    
#> b:(Intercept)    1.11216    0.45229  2.4589 0.01737 *  
#> c:(Intercept)  -46.62703  821.99546 -0.0567 0.95499    
#> d:(Intercept)  360.39895    4.96987 72.5168 < 2e-16 ***
#> e:(Intercept) 1106.80577 3076.84642  0.3597 0.72054    
#> ---
#> Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
#> 
#> Residual standard error:
#> 
#>  18.72333 (51 degrees of freedom)

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