# Statistics : Hypothesis Testing, Test Statistic and Critical Region

Please help answer the following questions involving statistics.

1. Why do we use hypothesis testing?

2. What is a test statistic and how is it related to a critical value in hypothesis testing?

3. What is the critical region in hypothesis testing and why is it important?

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#### Solution Preview

In practice, when we study a population or two populations, there may exist many parameters such as the mean and the standard deviation which are unknown. So we have to estimate them. Once we got an estimation, we have to test if the true value is equal (or close to) this value.

When we test if the true value is equal (or close to) this value, the first step we need to do is to set up the null hypothesis and alternative hypothesis. Then we ...

#### Solution Summary

The following posting helps with various statistics problems. Hypothesis testing, test statistics and critical regions are investigated. The solution is detailed and well presented. The response received a rating of "5" from the student who originally posted the question.