[R] Strange error message, many thanks

[David Winsemius]

On 3/21/20 9:35 AM, varin sacha via R-help wrote:
> Dear R-experts,
>
> Here below my R code giving an error message that I don't understand. If somebody can help me to fix it, it would be highly appreciated.
>
> # # # # # # # # # # # # # # # # # # # # # # # #
> install.packages( "robustbase",dependencies=TRUE )
> install.packages( "boot",dependencies=TRUE )
> library(boot)
> library(robustbase)
>
> n<-500
> b<-runif(n, 0, 5)
> z <- rnorm(n, 2, 3)
> a <- runif(n, 0, 5)
> df<-data.frame(b,z,a)
>
> y_model<- 0.1*b - 0.5 * z - a + 10
> y_obs <- y_model +c( rnorm(n*0.9, 0, 0.1), rnorm(n*0.1, 0, 0.5) )
Two errors: First, you need to have the y_obs vector in the df dataframe 
if you later reference it as a column.
>
>   # function to obtain MSE
>   MSE <- function(data, indices, formula) {
>      d <- data[indices, ] # allows boot to select sample
>      fit <- lmrob(formula, data = d)
>      ypred <- predict(fit)
>      mean((d[["y_obs "]] - ypred)^2)
The second error is the misspelling . Remove the space
>   }
>
>   # Make the results reproducible
>   set.seed(1234)
>   
>   # bootstrapping with 500 replications
>   results <- boot(data = df, statistic = MSE,
>                    R = 500, formula = y_obs ~ b+z+a)
>
> boot.ci(results, type="bca")


Now get:


 > boot.ci(results, type="bca")
BOOTSTRAP CONFIDENCE INTERVAL CALCULATIONS
Based on 500 bootstrap replicates

CALL :
boot.ci(boot.out = results, type = "bca")

Intervals :
Level       BCa
95%   ( 0.0237,  0.0460 )
Calculations and Intervals on Original Scale
Some BCa intervals may be unstable

-- 

David.

> # # # # # # # # # # # # # # # # # # # # # # # # #
>
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