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I am pulling a random sample from a list of prescription drugs and I want to make sure that my process is logical/valid.

I have a spreadsheet with 8100 rows of unique NDC numbers. Sometimes, in this list, more than one NDC number correspond to the same prescription drug. (For example, NDC #s 0093-4127-74 and 0093-4127-73 together count as 1 Penicillin).

I am thinking of using RAT-STATS to generate 50 numbers in sequential order (Samples) and 10 numbers in Random Order (spares) from the sampling frame 1 (low number) to 8100 (high number).

However, if by chance more than one of the 8100 NDC numbers, that correspond to the same drug, are randomly selected in the sample of 50, can I then use a spare that does not correspond to the same drug in order to have a total of 50 unique samples from the universe?

This is to avoid having to go through 8100 rows of NDC numbers and remove those that mean the same drug, and THEN run RAT-STATS. I hope I am making sense. Thank you in advance for the help.

I have a spreadsheet with 8100 rows of unique NDC numbers. Sometimes, in this list, more than one NDC number correspond to the same prescription drug. (For example, NDC #s 0093-4127-74 and 0093-4127-73 together count as 1 Penicillin).

I am thinking of using RAT-STATS to generate 50 numbers in sequential order (Samples) and 10 numbers in Random Order (spares) from the sampling frame 1 (low number) to 8100 (high number).

However, if by chance more than one of the 8100 NDC numbers, that correspond to the same drug, are randomly selected in the sample of 50, can I then use a spare that does not correspond to the same drug in order to have a total of 50 unique samples from the universe?

This is to avoid having to go through 8100 rows of NDC numbers and remove those that mean the same drug, and THEN run RAT-STATS. I hope I am making sense. Thank you in advance for the help.

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If you are asking for the probability that 50+10 will be enough, that would depend on how often different numbers corespond to the same drug.

Also I am unsure of the difference between 50 numbers in sequential order and 10 numbers in Random Order.

Is there any order to the NDC numbers? Why are your first 50 numbers not random?

When you draw your sample can you not check then for duplication? (and discard the duplicate.

From the description of the random generator you are using, it would appear it's a resampling without replacement, explaining why you need to generate all numbers at once. In that case, it it valid to reject duplicates after sampling (using the “spares”). You are basically selecting different drugs each with the same probability, accepting any representative (any of its numbers).

Whether any inference based on unweighted sampling is valid it another question. In any case, you are assuming the universe (your list) to be a valid representation of the reality you are studying, or you are studying the list itself.

(°v°)

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