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From: rynn on 3 Mar 2010 06:02
Hi,

Can anyone help me on how to generate random number with this condition:-
1) I have 100 data and want to select 10 sample. However, I have to repeat choosing the 10 sample for 30 times.
2) the model that I want to develop here is nonlinear model with 1 output and 4 input variables (x1,x2,x3,x4). So I got confusing about which variables or only output data that I have to use in order to generate a random sample.

Thanks in advance..

rynn.
From: Walter Roberson on 3 Mar 2010 14:20
rynn wrote:
> Hi,
>
> Can anyone help me on how to generate random number with this condition:-
> 1) I have 100 data and want to select 10 sample. However, I have to
> repeat choosing the 10 sample for 30 times.

With or without replacement for each trial?

If it is without replacement, then:

[a,b] = sort(rand(100,30));
selectedsamples = samples(b(1:10,:));

Each column will be the samples for one trial. (I put them into columns
because you probably want to access a trial at a time and access along columns
is faster in Matlab.)

> 2) the model that I want to develop here is nonlinear model with 1
> output and 4 input variables (x1,x2,x3,x4). So I got confusing about
> which variables or only output data that I have to use in order to
> generate a random sample.

It is not clear how the second part of your question relates to the first
part? Is the probability of selection of particular samples non-uniform? If so
then with or without replacement??
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