Lec29 Standard Errors Part II

Recall

• 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!

Announcements

• PS-10 Discussion.
• Regular lecture during lab time tomorrow.
• Doodle Poll to fill 11 time slots to discuss projects, as a group.

In-Class

Learning checks: Based on

• the example in the Lec27-B learning check discussion
• the chalk talk notes from Lec28

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

• Lec29 learning check discussion