Sampling24Cats

Random Sampling with the Cat data set CCSS 7.SP.1 Introduction to simple random sampling, stratified sampling and systematic sampling with a TinkerPlots Mixer.

TP file with Task A and B - Updated July 10th, 2017

Task A - Simple Random Sample
Set the sampler to the number of cats you want in the sample. Caution: Make sure that without replacement is selected.

Task B - Stratified Sampling
Create a Stratified Random Sample of 4 cats. Since we have an equal number of males and females we can use a Sampler with a Counter and two Mixers.

The counter shows the categories Male and Female. The names of the male cats are put into the top mixer with a branch going up. The names of the female cat are in the mixer on the lower branch. If you want a sample with two female cats for every male cat, you would need an additional "Female" option to the counter.

Task C - Systematic Random Sample
Create a Systematic Sample of 5 cats.

Step 1. Use the sampler from Task A but set the Repeat to 24 (all cats).

Step 2. Randomly select a number from 1-4 and then use every fifth occurrence of this value to create your sample of 5 cats.

This is technically NOT a random sample because the cats do not have an equal chance of being selected. Systematic samples use the kth element in a list of the population.

IMPORTANT When creating a random sample, ask yourself if EACH item, person, or cat in the population has an EQUAL chance of being selected. “Randomly” surveying students in the cafeteria does not produce a random sample, why not?


 * Reminder: A sample represents the population that it is selected from.