Hypotheses & Hypothesis tests 

Hypothesis and Hypothesis Testing
Hypothesis testing is a subfield of inferential statistics. Always two hypotheses are formulated, which assert the opposite.
Null hypothesis H0:
The null hypothesis assumes that there is no difference in a characteristic between two or more groups.
Alternative hypothesis H1:
Alternative hypotheses, on the other hand, assume that there is a difference between two or more groups.
In addition, there are several types of hypotheses
Directional and non-directional (one-tailed and two-tailed)
difference and correlation hypotheses
Hypothesis are used when you want to draw conclusions about a population based on a sample. So always, if you want to prove or say something about the population with a sample.
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Mann-Whitney U-test:
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Correlation:
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Regression:
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