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https://www.youtube.com/watch?v=qkmRA2D0W0Y&list=PLsri7w6p16vvQCo9pmuRNY_SYoOGB6bWM&index=2
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Population A and population B are independent
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independent samples' parameters and statistical values
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When variance of 2 populations is same,
comparison is simple
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When variance is different,
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Cases are 4
1. "enough sample", "variance of 2 populations are same"
2. "enough sample", "variance of 2 populations are unknown"
3. "not enough sample", "variance of 2 populations are same"
4. "not enough sample", "variance of 2 populations are unknown"
* Enough sample means sample $$$\gt$$$ 30
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