st: creating random groups of observations

[Luca Campanelli <l.campanelli@yahoo.it>]

I apologize for my previous email with no subject. 


Dear Stata users,
I have a string variable "word" with 4000 words, and I'd like to create 1000 groups of 4 randomly selected words (the group of words will be trials in an experimental task). I also have info about the number of characters of each word.

The dataset:
   ID   WORD      CHR
   1    acorn     5
   2    address   7
   3    adult     5

One way to do it could be:
   generate rdm = runiform()
   sort rdm
   egen group = seq(), from(1) to(1000) block(1)

My question is if I can constrain the groups to meet a certain criterion: I'd like that each group of words has a total number of characters between given limits, for example between 18 and 28 total number of characters. I mean that I don't want groups with 4 short words or groups with 4 long words.
Do you know if there is any way to do it?

Thank you for any help anybody can provide.
Luca Campanelli

PS I have Stata IC 12.1 on Windows 7.


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