Jeph suggests the ceil() solution in a follow-up with the caveat "as
long as uniform() never returns precisely 0, which I've
never seen" --uniform() is 0 with probability about 1 in 4 billion, so
to be safe you could
gen y = x[ceil(_N*(1-uniform()))]
On Thu, Feb 26, 2009 at 2:33 PM, Austin Nichols <[email protected]> wrote:
> With replacement:
> gen y = x[round(_N*uniform(),1)+1]
>
> should be
> gen y = x[round(_N*uniform()+.5)]
> or
> gen y = x[ceil(_N*uniform())]
>
> I think.... (otherwise you can get _N+1 in the square brackets, for a
> missing y, and the prob of getting y[1] is too low)
>
> On Thu, Feb 26, 2009 at 2:19 PM, Jeph Herrin <[email protected]> wrote:
>>
>> It's not clear if you want sampling with or without replacement.
>>
>> With replacement:
>>
>> gen y = x[round(_N*uniform(),1)+1]
>>
>> without replacement:
>>
>> egen index=rank(uniform())
>> gen y = x[index]
>>
>> hth,
>> Jeph
>
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
