This is personal study note Copyright and original reference: https://www.youtube.com/watch?v=qkmRA2D0W0Y&list=PLsri7w6p16vvQCo9pmuRNY_SYoOGB6bWM&index=2 ================================================================================ On 2 populations - About the mean difference - Test hypothesis - Independent sample ================================================================================ 1. What is independent sample 2. Case1: enough sample, you know population standard deviation 3. Case2: enough sample, you don't know population standard deviation 4. Case3: not enough sample, you know population standard deviation 5. Case4: not enough sample, you don't know population standard deviation ================================================================================ ================================================================================ ================================================================================ Parameter and statistic of "independent sample" Sample a and b can be enough or not-enough ================================================================================ Due to above characteristic, variance information is important ================================================================================