• Thought Experiment: Sample 3 students at random and get their (sample) mean age. Do this many, many, many only 3 times
  • Question 1: Why do the sample means below vary?
  • Answer 1: Because of the sampling variability induced by the random sampling!
  • Question 2: What value quantifies how much these sample means vary by?
  • Answer 2: The Standard Error!
Random Sample (Sample) Mean Age
Jack, Jared, Sam 21.7
Wengel, Rebecca, Steven 19.4
Stefan, Joccelyn, Sierra 20.0



Learning checks: Based on

  1. Explicity compute the standard error when taking samples of size n=5 and n=50.
  2. Discuss with your peers why they matter in any study that involves some kind of sampling.

After-Class Updates