# Decision Errors: Alpha and Power Relationship

This is the second part of the last work you did help me with,Turning Research Questions into Hypotheses "The higher body height the more frequent heart disease".

a. Restate your Research Question and Hypotheses: In Unit 4 you began to study the use of hypothesis testing to answer research questions. Rewrite your research question, null hypothesis, and alternative hypothesis from Unit 5 here. Make any needed improvements or corrections based on feedback from the Unit 4 Discussion Board.

b. Population(s) and Sample(s): Given your research question and hypothesis above, what would be your population of interest? Describe the sample you might collect, including sampling method and size to conduct your test of hypothesis.

c. Select a Level for Alpha: Select the level of alpha (α) that you would use in testing your hypotheses. Be sure to think about the criticality of committing a Type I or Type II error before just selecting the conventional α = .05. Which type of error is worse, and why?

d. Power and Effect Size:Suppose the effect size of your research study is very large. What does this tell you about your results? If you were not able to reject the null hypothesis and determined that the statistical power of the study was low, what could you do to increase the statistical power if you were to replicate your study?

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#### Solution Preview

a. Restate your Research Question and Hypotheses: In Unit 4 you began to study the use of hypothesis testing to answer research questions. Rewrite your research question, null hypothesis, and alternative hypothesis from Unit 5 here. Make any needed improvements or corrections based on feedback from the Unit 4 Discussion Board.

Answer: research question: we want to know if there is a relationship between body height and frequency of heart disease. If yes, what is the relationship it is exactly? Positive or negative?

null hypothesis: there is no relationship between body height and frequency of heart disease

alternative hypothesis: there is a relationship between body height and frequency of heart disease

b. Population(s) and Sample(s): Given ...

#### Solution Summary

The solution gives detailed analysis on relationship between level of alpha and power, also the concept of type I and type II errors.