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## High school statistics

### Course: High school statistics>Unit 5

Lesson 3: Sampling methods

# Techniques for generating a simple random sample

Techniques for generating a simple random sample.

## Want to join the conversation?

• How does one ensure that the random digit table (the list of numbers) is actually random? Isn't using a random digit table almost the same as me writing out "random" numbers because to begin with, that list of numbers was created by me anyways?
• There isn't really a way of knowing if a random digit table is actually random. But if you were to write out a list of random numbers, you could get rid of the "randomness" of the numbers accidentally if you put any thought into the numbers. Or your subconscious might have a method to picking your "random numbers" that you do not know about. So using a random digit table is better since it does not have any apparent bias or method as to how those numbers were chosen.
• At Sal talks about using a random digit table. In his example, he took two consecutive digits and then moved to the next two consecutive digits to get 59, 83, 35, 59, 37, .... Would it have been legitimate to have just moved one digit at a time rather than two to get 59, 98, 83, 35, 59, 93, 37, ...?
• I had the same in mind. The answer is: You have to assign each of your cases a random number to pick that has the same number of digits than your largest case.
Let's say we have 1, 2, 3 .. 25 cases,
then we assign the following random numbers: 01, 02, 03, .. 24, 25.
• At , How is choosing people with numbers assigned from 01 to 80 random? The person which is assigned the number 80 will have the least chance of being chosen because there are so many other 70's, 60's.... Shouldn't a random sample have everything in it equally likely?
• it is equal because the person who is number 76 has the same amount of chance as being chosen with a person who has number 80. They are just numerical place holders to facilitate the generating process.
• What are the methods of obtaining random samples
• will I use this in the real world?
• Could you generate a random digit table by putting the digits 0-9 on a slip of paper, putting those slips in a tumbler, blindly drawing a digit, writing its value on the table, and then immediately placing the digit back in the tumbler before spinning and drawing again?

What are some other examples of how these tables are created?
• Yes, this is a possible way to make a random digit table, as long as the slips are replaced. Another example would be to use a calculator function or computer program to generate the random numbers for you. A final example would be rolling a 10 sided die.
• At if you go with the randomly generated list of numbers, do you get a truly random sample if the randomly generated list of numbers has repeated digits.

Eg. if instead of starting with 5983... the number starts with 5959.. Does this lead to any bias in the sample.
• Human generated "random numbers" will avoid duplicates, however a true random set of numbers does not take into consideration what any of the numbers before it were it is completely random so a chart could start with repeated numbers and not be biased.
(1 vote)
• Are there any other techniques for this simple random sample.
• I want to point out that using a computer to get a bunch of "random" numbers is not good if it really matters that everything actually truly is random because computers cannot actually generate a list of completely random numbers.
(1 vote)
• How does one ensure that the random digit table (the list of numbers) is actually random? Isn't using a random digit table almost the same as me writing out "random" numbers because to begin with, that list of numbers was created by me anyways?
(1 vote)