AS/A2 Stats 1 Stats 2

S3 Topic 2: Sampling
Use of random numbers
You are to obtain a random sample from the numbers 101 to 200. Simple random sampling Choose the size of your sample. Then click on Make a selection. Random numbers from 1 to 1000 will be given. Only those from 101 to 200 - and which have not been chosen before - will be added to your required random sample.

Sample size: 1 5 10 15 20

Samples taken

Your random sample

Improved random sampling Choose the size of your sample. Then click on Make a selection. Random numbers from 1 to 1000 will be given. Each will be reduced or increased to a number between 101 and 200 by subtracting multiples of 100 and those which have not been chosen before will be added to your required random sample.

Sample size: 1 5 10 15 20

Samples taken

Your random sample

Summary You will find that simple random sampling requires a lot of selections to be made before you get your required sample size - approximately ten times as many. With improved random sampling, this total number is greatly reduced. © MathsNet 2001