# [R] Calculating confidence in an estimate including numberof trials?

Zembower, Kevin kzembowe at jhuccp.org
Tue Oct 16 22:44:54 CEST 2007

```Daniel, thanks for your suggestion. So, it's just done like this:
> pnorm(21, mean=20, sd=10/4) - pnorm(19, mean=20, sd=10/4)
[1] 0.3108435
> # OR
> pnorm(21, mean=20, sd=10/sqrt(16)) - pnorm(19, mean=20,
sd=10/sqrt(16))
[1] 0.3108435
>

Thanks, again.

-Kevin

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of Daniel Lakeland
Sent: Tuesday, October 16, 2007 4:35 PM
To: r-help at r-project.org
Subject: Re: [R] Calculating confidence in an estimate including
numberof trials?

On Tue, Oct 16, 2007 at 04:30:48PM -0400, Zembower, Kevin wrote:

> Now I'd like to know how to use R to solve this type of problem. In
all
> my other problems using normal curves, I used dnorm or pnorm, but
> neither of these includes anything regarding the number of trials.

pnorm can be used like your table of area under the normal curve. To
account for size of sample you have to scale the variance
appropriately according to the theory you have learned in your course.

--
Daniel Lakeland
dlakelan at street-artists.org
http://www.street-artists.org/~dlakelan

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