# Re: [R] Binomial

From: Sarah Sanchez <sarah_sanchez09_at_yahoo.com>
Date: Thu, 12 May 2011 06:04:35 -0700 (PDT)

Thanks a lot sir.

Regards

Sarah

• On Thu, 5/12/11, Alexander Engelhardt <alex_at_chaotic-neutral.de> wrote:

From: Alexander Engelhardt <alex_at_chaotic-neutral.de> Subject: Re: [R] Binomial
To: "Sarah Sanchez" <sarah_sanchez09_at_yahoo.com> Cc: "David Winsemius" <dwinsemius_at_comcast.net>, r-help_at_r-project.org Date: Thursday, May 12, 2011, 12:53 PM

Am 12.05.2011 13:19, schrieb Sarah Sanchez:
> Dear R helpers,
>
> I am raising one query regarding this "Binomial" thread with the sole intention of learning something more as I understand R forum is an ocean of knowledge.
>
> I was going through all the responses, but wondered that original query was about generating Binomial random numbers while what the R code produced so far generates the Bernoulli Random no.s i.e. 0 and 1.
>
> True Binomial distribution is nothing but no of Bernoulli trials. As I said I am a moron and don't understand much about Statistics. Just couldn't stop from asking my stupid question.

Oh, yes.
You can generate one B(20,0.7)-distributed random varible by summing up the like this:

> pie <- 0.7
> x <- runif(20)
> x

``` [1] 0.83108099 0.72843379 0.08862017 0.78477878 0.69230873 0.11229410
[7] 0.64483435 0.87748373 0.17448824 0.43549622 0.30374272 0.76274317
[13] 0.34832376 0.20876835 0.85280612 0.93810355 0.65720548 0.05557451
[19] 0.88041390 0.68938009
```

> x <- runif(20) < pie
> x
[1] FALSE FALSE  TRUE FALSE  TRUE  TRUE  TRUE  TRUE FALSE  TRUE FALSE  TRUE [13] FALSE FALSE  TRUE  TRUE FALSE  TRUE FALSE FALSE
> sum(x)

[1] 10

You could shorten this to

> sum(runif(20)<0.7)
[1] 12

Which would be the same as

> rbinom(1,20,0.5)
[1] 6

or even

Just play around a little, and learn from the help files:

> ?rbinom

Have fun!

>
> --- On Thu, 5/12/11, David Winsemius<dwinsemius_at_comcast.net>  wrote:
>
> From: David Winsemius<dwinsemius@comcast.net>
> Subject: Re: [R] Binomial
> To: "Alexander Engelhardt"<alex_at_chaotic-neutral.de>
> Cc: r-help_at_r-project.org, "blutack"<x-jess-h-x_at_hotmail.co.uk>
> Date: Thursday, May 12, 2011, 11:08 AM
>

He didn't, or better, he forgot.
Also, that Allan isn't related to me (I think) :)

• Alex

[[alternative HTML version deleted]]

R-help_at_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. Received on Thu 12 May 2011 - 14:55:15 GMT

This quarter's messages: by month, or sorted: [ by date ] [ by thread ] [ by subject ] [ by author ]

Archive maintained by Robert King, hosted by the discipline of statistics at the University of Newcastle, Australia.
Archive generated by hypermail 2.2.0, at Thu 12 May 2011 - 15:00:06 GMT.

Mailing list information is available at https://stat.ethz.ch/mailman/listinfo/r-help. Please read the posting guide before posting to the list.