This demonstration illustrates the difference between simple random sampling and stratified sampling. The population consists of 100 animals: 60 lions, 30 turtles, and 10 rabbits. The default is for random sampling. If you push the "sample 10 animals" button, 10 animals will be sampled and the number of lions, rabbits, and turtles will be tabulated and shown. The animals sampled are shown in blue. If you push the button again, another sample will be drawn and the new tally will be shown to the right of the first tally.
To start over, click the "reset" button.
If you choose "stratified sampling" then the composition of the sample will match that of the population.
The opening screen of the sampling simulation displays all 100 animals in the population.
You can select between a random sample and a stratified sample directly below the population and then generate a sample of ten animals.
Below is an example of a random sample. Notice that animals selected are highlighted in the population and the total number of animals selected from each category is listed at the bottom of the simulation.
We recommend you answer the questions even if you have to guess. Then use the simulation to help you verify your answers. After interacting with the simulation click the "Check Answer" button.
To start, select Random or Stratified sample. Each time you click the "Sample 10 animals" the number sampled from each category is displayed.