Aim: How do we use random sampling?

What is random sampling? Method 1

• Most popular method is to place identification of participants on a card, place in a bowl and select as many cards needed at random– The subjects whose cards are selected constitute

the sample– Since it is difficult to mix card thoroughly, there is

a chance of obtaining a biased sample• Therefore we use another method of generating

random samples

What is random sampling? Method 2

• The second, more efficient way to obtain a truly random sample is using a generated random number grid

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What are random numbers?

• Random numbers are sets of digits (i.e., 0, 1, 2, 3, 4, 5, 6, 7, 8, 9) arranged in random order.

• Because they are randomly ordered, no individual digit can be predicted from knowledge of any other digit or group of digits.

What is a random number generator?

• A random number generator is a process that produces random numbers.

• Any random process (e.g., a flip of a coin or the toss of a die) can be used to generate random numbers.

What is a random number table?

• A random number table is a listing of random numbers

• Based on the following User specifications: – The quantity of random numbers desired.– The maximum and minimum values of random

numbers in the table.– Whether or not duplicate random numbers are

permitted.

How do we use the random digits? • Table A Random Digits (handout)

Example: The following 10 students need to be selected at random to enter a contest in their local school newspaper. Use the table of random digits to find their order. Be sure to say where you entered the table and how you used it.

Amber ConoMatthew TomStephanie JudyJade AlexJessica Chris

Class Work

• Complete Handout