[R] how to generate a normal distribution with mean=1, min=0.2, max=0.8
David Winsemius
dwinsemius at comcast.net
Fri Apr 29 19:45:31 CEST 2011
On Apr 29, 2011, at 1:29 PM, Mike Miller wrote:
> On Fri, 29 Apr 2011, Giovanni Petris wrote:
>
>> Well, but the original poster also refers to 0.2 and 0.8 as
>> "expected min and max", in which case we are back to a joke...
>
> Well, he is a lot better with English than I am with Mandarin. He
> seemed to like the truncated normal answers, so we'll let those be
> his answers.
>
> It is possible to choose parameters for a normal distribution with
> 500 observations such that the expected value of the maximum is .8
> and the expected value of the minimum is .2. Obviously, the mean
> would be .5, not 1, but what would the variance then have to be to
> provide the correct expected max and min? That's another legitimate
> question.
You would need to specify an N since the expected first and last order
statistic would decrease/increase with increasing N.
--
David.
>
> Mike
>
>
>>>> -----Original Message-----
>>>> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org
>>>> ] On Behalf Of Mao Jianfeng
>>>> Sent: Thursday, April 28, 2011 12:02 PM
>>>> To: r-help at r-project.org
>>>> Subject: [R] how to generate a normal distribution with mean=1,
>>>> min=0.2, max=0.8
>>>>
>>>> Dear all,
>>>>
>>>> This is a simple probability problem. I want to know, How to
>>>> generate a normal distribution with mean=1, min=0.2 and max=0.8?
>>>>
>>>> I know how the generate a normal distribution of mean = 1 and sd
>>>> = 1 and with 500 data point.
>>>>
>>>> rnorm(n=500, m=1, sd=1)
>>>>
>>>> But, I am confusing with how to generate a normal distribution
>>>> with expected min and max. I expect to hear your directions.
>>>>
>>>> Thanks in advance.
>>>>
>>>> Best,
>>>> Jian-Feng,
David Winsemius, MD
West Hartford, CT
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