R programming drc package error

Question

I'm a new bee to R programming. My problem is, how do I get the standard deviations for each concentration (0,1,5,10,15,20 mg/L) to get displayed on the plot?

Here's my code:

    72 timer LC50
> LC50_72hR<-read.csv(file.choose(),dec=".",sep=" ", header=TRUE)
> LC50_72hR
   Concentration Total Dead
1              0    20    1
2              0    20    1
3              0    20    1
4              1    20    4
5              1    20    2
6              1    20    5
7              5    20    7
8              5    20   11
9              5    20   10
10            10    20   11
11            10    20   16
12            10    20   15
13            15    20   16
14            15    20   18
15            15    20   20
16            20    20   19
17            20    20   20
18            20    20   20
> LC50_72hR<-drm(Dead/Total~Concentration,weights=Total,fct=LL.2(),type="binomial",data=LC50_72hR)
> summary(LC50_72hR)

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:(Intercept) -1.40548    0.16443 -8.54734       0
e:(Intercept)  4.09353    0.49499  8.26987       0
> plot(LC50_72hR)
> ED(LC50_72hR,c(10,50,90))

Estimated effective doses

     Estimate Std. Error
1:10  0.85734     0.2242
1:50  4.09353     0.4950
1:90 19.54538     3.2559

How do I put std dev on my plot?

Answer 1

You need two variables, (x and y). In the regression, you divided dead/total means this is one variable (x) and you have another variable for concentration. This way you can easily plot the SD on your data.