Testing
Lecture 22
Dr. Elijah Meyer + Konnie Huang
Duke University
STA 199 - Fall 2022
November 14th, 2022
Announcements
– Lab 7 Due Tonight (Monday)
– Exam Week! Please vote on review survey
Goals
– Compare two proportions, and do a hypothesis test
– Compare two means, and do a bootstrap interval
– Prediction and bootstrap interval for the slope
Can we always make inference?
– Short answer no
– An assumption that we need to make is called independence in order to trust our simulation results.
Warm up: Independence
– What is independence?
- One observation does not effect or influence another
Independence Example
– 50 Airbnb listings in 2020 for Asheville, NC.
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How do we ensure independnece
– Random Sample - Every observation has an equal probability of being selected
– A random sample ensures that our sample is representative of the entire population
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If we don’t have a random sample …
– Our results are hard to trust
– Good models and procedures can not fix bad data
For your project
– Today, we go through how to bootstrap for a slope coefficient
– Can use other bootstrap methods for other questions you may be interested in
– Do not use if data are not representitative
In Summary
