R help - Oct 2010 - Please help me about Monte Carlo Permutation

> Dear R experts,
>I am sorry for my inability.
>I have the following dataset:
 > Qtot Itot
>1   73  684
>2   64  451
>3   71  378
>4   65  284
>5   47  179
>6   31  117
>7   19   69
>
>Now I need to perform Monte Carlo Pertutation test underlaying the
following condition.
>
>
>Condition
>
>In order to choose randomly (5000 times) for the Qtot in the interval 0 to
the maximum possible value of
>
>Qtot for each observed value of the independent variable (Itot), Monte
Carlo tests needed to be perform to test the null hypothesis.
The
>maximum observed value is either the calculated size of the regional pool
(Interpolated value), or the measured size of the actual
>
>pool. Each time correlation coefficient (r) between independent and
dependent variable has to be calculated in order to
achieve
>
>the empirical distribution of r for the null hypothesis conditions.
>
>Now please help me how to do?
>I have also intalled combinat library in R. But could not perform by
myself.
>I will be highly grateful.
>Thanks.
>
-->
Chitra Bahadur Baniya (PhD)
Lecturer
Central Department of Botany
Tribhuvan University
Kirtipur
Kathmandu, Nepal

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This is one way. I read your two columns of data into
two variables, x and y. Then:

 test <- replicate(5000, cor(x, sample(y)))
> hist(test)

Kjetil

On Thu, Oct 28, 2010 at 9:49 AM, Chitra <cbbaniya at gmail.com>
wrote:
>
>> Dear R experts,
>>I am sorry for my inability.
>>I have the following dataset:
>
> ?> Qtot Itot
>>1 ? 73 ?684
>>2 ? 64 ?451
>>3 ? 71 ?378
>>4 ? 65 ?284
>>5 ? 47 ?179
>>6 ? 31 ?117
>>7 ? 19 ? 69
>>
>>Now I need to perform Monte Carlo Pertutation test underlaying the
> following condition.
>>
>>
>>Condition
>>
>>In order to choose randomly (5000 times) for the Qtot in the interval 0
to
> the maximum possible value of
>>
>>Qtot for each observed value of the independent variable (Itot), Monte
> Carlo tests needed to be perform to test the null hypothesis. The
>>maximum observed value is either the calculated size of the regional
pool
> (Interpolated value), or the measured size of the actual
>>
>>pool. Each time correlation coefficient (r) between independent and
> dependent variable has to be calculated in order to achieve
>>
>>the empirical distribution of r for the null hypothesis conditions.
>>
>>Now please help me how to do?
>>I have also intalled combinat library in R. But could not perform by
> myself.
>>I will be highly grateful.
>>Thanks.
>>
> -->
> Chitra Bahadur Baniya (PhD)
> Lecturer
> Central Department of Botany
> Tribhuvan University
> Kirtipur
> Kathmandu, Nepal
>
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> View this message in context:
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> Sent from the R help mailing list archive at Nabble.com.
>
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>
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>

Dear Kjetil,
Thanks a lot for your help. I could not get histogram when I ask by R. It
simply gave me blank plot between frequency and test. I want to plot sample
(y) verses xl. Can you please tell me are both variables were permuted or
only x?
Thanking your help,
Chitra
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