This is personal study note
Copyright and original reference:
https://www.youtube.com/watch?v=fx4tCRiynMQ&list=PLsri7w6p16vtEz_J1G7HQG-Rm8vpZPtPS&index=3
================================================================================
Test on hypothesis (about estimated population mean)
- when you don't know population's variance
================================================================================
If number of sample $$$n \to \infty $$$,
"sample std" becomes "population std" regardless of population's normality
- use z statistics
================================================================================
When you have small number of sample
use t-statistics
use "sample std"
================================================================================
Relation between t and z
z: special case (when you have enough number of sample)
================================================================================
Example
statistic t