Sampling from a box of apples
Interest in specific numerical or categorical characteristics
Many characteristics vary from apple to apple — no two are alike.
Some apples are bruised, so select Apple condition from the pop-up menu on the right to illustrate sampling this characteristics of the apples. Similarly illustrate sampling the Weights of the apples.
We usually abstract by considering sampling of numbers or categories.
Variability of sample statistics
While displaying the Apple condition (as ticks and crosses), click Propn(Bruised) to see the proportion of bruised apples in the box (population) and sample. Discuss the sample-to-sample variability in sample proportions and the difference between the sample and population proportions (sampling error).
When displaying their Weights, similarly discuss the variability of the sample mean and its sampling error.