Hi > -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-bounces@r- > project.org] On Behalf Of Clive Nicholas > Sent: Monday, November 12, 2012 8:06 AM > To: r-help@r-project.org > Subject: [R] Bootstrapping issues > > sessionInfo()R version 2.15.2 (2012-10-26) > Platform: i686-pc-linux-gnu (32-bit) > > locale: > [1] LC_CTYPE=en_GB.UTF-8 LC_NUMERIC=C > LC_TIME=en_GB.UTF-8 > [4] LC_COLLATE=en_GB.UTF-8 LC_MONETARY=en_GB.UTF-8 > LC_MESSAGES=en_GB.UTF-8 > [7] LC_PAPER=C LC_NAME=C > LC_ADDRESS=C > [10] LC_TELEPHONE=C LC_MEASUREMENT=en_GB.UTF-8 > LC_IDENTIFICATION=C > > attached base packages: > [1] stats graphics grDevices utils datasets methods base > > other attached packages: > [1] boot_1.3-7 > > loaded via a namespace (and not attached): > [1] tools_2.15.2 > > > Hello. I have a very straightforward question. Here's some simulated > data > (N=500) > > test<-data.frame(A=rnorm(500,mean=2.72,sd=5.36), > B=sample(c(12,20,24,28,32),size=500,prob=c(0.333,0.026,0.026,0.436,0.17 > 9),replace=TRUE),C=sample(c(0,1),size=500,replace=TRUE),D=sample(c(0,1) > ,size=500,replace=TRUE)) > > > head(test) A B C D > 1 1.181804 28 1 0 > 2 -5.602307 12 1 1 > 3 2.925090 24 1 1 > 4 3.437408 28 1 0 > 5 -6.503531 32 0 0 > 6 11.013888 12 1 1 > > > which I then bootstrap using > > library(boot) > > bs <- function(formula, data, indices) { test <- data[indices,] > fit <- lm(formula, data=test) return(coef(fit)) > > } > > > The following works > > results <- boot(data=test, statistic=bs, R=1000, A~B+C+D+C*D) >
Actually it does not work either > results <- boot(data=test, statistic=bs, R=1000, A~B+C+D+C*D) Error in data[indices, ] : incorrect number of dimensions > I am not sure but I suspect your bs function expects some indices vector and it is somehow not in accordance with your data. Regards Petr > > results > > > But when I then amend the dataset by changing the D variable to > simulate fixed proportions > > D=sample(c(0,1),size=500,prob=c(0.564,0.436),replace=TRUE > > > head(test) A B C D > 1 5.73771963 28 0 1 > 2 -0.19040750 12 1 0 > 3 2.22515982 12 0 1 > 4 -0.02905223 32 1 0 > 5 4.68314112 28 0 1 > 6 5.10711732 12 1 0 > > > the same bootstrapping routine chokes with an error > > results <- boot(data=test, statistic=bs, R=1000, A~B+C+C*D)Error in > data[indices, ] : incorrect number of dimensions > > > despite the fact that the B variable also has simulated fixed > proportions and yet the original code ran without any errors. I have > two general observations to make about this: > > (1) this does not make sense; and > (2) I don't understand this. > > How best to make these two observations go away and run the code to my > satisfaction? > > Many thanks. > > -- > Clive Nicholas (clivenicholas.posterous.com) > > [Please DO NOT mail me personally here, but at > <clivenicho...@hotmail.com>. > Please respond to contributions I make in a list thread here. Thanks!] > > "My colleagues in the social sciences talk a great deal about > methodology. > I prefer to call it style." -- Freeman J. Dyson > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting- > guide.html > and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
