# about the 95%CI around the median...

5 messages
Open this post in threaded view
|

## about the 95%CI around the median...

 Dear people I've learnt that by using the "boxplot.stats" command in the "grDevices" library I can get the 5-number summaries of a boxplot, plus other important information, like the confidence interval around the median. I'm interested in knowing the actual formula to used in that package to calculate that confidence interval. Can someone help me with this? Cheers, Fernando ______________________________________________ [hidden email] mailing list https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.
Open this post in threaded view
|

## Re: about the 95%CI around the median...

 See ?fivenum in the stats package. If you just type stats::fivenum you will get the code. The crucial calculations are in the last few lines. Simon. On Mon, 2008-08-04 at 16:19 +0930, Fernando Marmolejo Ramos wrote: > Dear people > > I've learnt that by using the "boxplot.stats" command in the "grDevices" library > I can get the 5-number summaries of a boxplot, plus other important information, > like the confidence interval around the median. > > I'm interested in knowing the actual formula to used in that package to > calculate that confidence interval. > > Can someone help me with this? > > Cheers, > > Fernando > > ______________________________________________ > [hidden email] 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. -- Simon Blomberg, BSc (Hons), PhD, MAppStat. Lecturer and Consultant Statistician Faculty of Biological and Chemical Sciences The University of Queensland St. Lucia Queensland 4072 Australia Room 320 Goddard Building (8) T: +61 7 3365 2506 http://www.uq.edu.au/~uqsblombemail: S.Blomberg1_at_uq.edu.au Policies: 1.  I will NOT analyse your data for you. 2.  Your deadline is your problem. The combination of some data and an aching desire for an answer does not ensure that a reasonable answer can be extracted from a given body of data. - John Tukey. ______________________________________________ [hidden email] mailing list https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.
Open this post in threaded view
|

## Re: about the 95%CI around the median...

 On Mon, 2008-08-04 at 17:00 +1000, Simon Blomberg wrote: > See ?fivenum in the stats package. If you just type > > stats::fivenum > > you will get the code. The crucial calculations are in the last few > lines. That will only give the code to calculate the five number summary, but Fernando wants to know how the confidence interval is calculated in boxplot.stats. To see the code just type boxplot.stats followed by return at the command line in R. The relevant line is:     conf <- if (do.conf)         stats[3] + c(-1.58, 1.58) * iqr/sqrt(n) Which is working on the median (stats[3]). Details of this computation are in ?boxplot.stats which should have been Fernando's first port of call. Two works are cited in support of the calculation with full references in the References section of that help page. HTH G > > Simon. > > On Mon, 2008-08-04 at 16:19 +0930, Fernando Marmolejo Ramos wrote: > > Dear people > > > > I've learnt that by using the "boxplot.stats" command in the "grDevices" library > > I can get the 5-number summaries of a boxplot, plus other important information, > > like the confidence interval around the median. > > > > I'm interested in knowing the actual formula to used in that package to > > calculate that confidence interval. > > > > Can someone help me with this? > > > > Cheers, > > > > Fernando > > > > ______________________________________________ > > [hidden email] 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. ______________________________________________ [hidden email] mailing list https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.