topic Re: Random - Sample Size in Table --> Subset ---- What is the function that is used to create the randomness in selections? in Discussions

Random - Sample Size in Table --> Subset ---- What is the function that is used to create the randomness in selections?

CramerRaoError1 — Wed, 08 May 2024 14:13:40 GMT

I want to know what function/algorithm was used to generate the randomness in selecting the samples when we use the random - sample size option when subsetting a table in JMP.

Re: Random - Sample Size in Table --> Subset ---- What is the function that is used to create the randomness in selections?

peng_liu — Mon, 13 May 2024 03:22:36 GMT

If you are asking whether it is with or without replacement, the answer is without replacement. If the subset size equals the original size, the result is a random shuffle: https://www.jmp.com/support/help/en/18.1/#page/jmp/create-a-subset-data-table.shtml?os=win&source=application#ww320919

Re: Random - Sample Size in Table --> Subset ---- What is the function that is used to create the randomness in selections?

MRB3855 — Mon, 13 May 2024 08:13:33 GMT

Hi @CramerRaoError1 : Further to @peng_liu 's comment. Effectively, it is the same as the following; say you want a random subset of size n.

1. Assign each row a random number (each Uniformly distributed between 0 and 1).

2. Sort the Rows by the Uniform number.

3. Take the top n rows as the random subset of size n,

There are other methods...but, they all boil down to each sample of size n having equal probability of being selected. So, in that sense, the methods are all equivalent.