STA 6166 UNIT 5 Section 1 Answers
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1. What is the difference between observational and experimental studies?
2. What is the difference between the two methods of controlling crucial factors in experiments?
3. List the items that should be included in a experimental plan.
4. Define treatment and factor. Give examples from your field of study at to what is a factor and what is a treatment.
5. Give an example of a factorial set of treatments?
6. What is a control treatment and why is it important in most experimental studies?
7. What is an experimental unit? How is it different from the measurement unit?
8. What do we mean by replication of a treatment in an experiment?
9. Is "experimental error" really a mistake?
10. What is the important role of the measurement of the variance of the experimental error?
11. What do we mean when we talk about "control"?
12. What is a block, and why is it an important tool in experimental design?
13. What is a covariate?
14. Does it make a difference if we talk about randomizing treatments to experimental units or randomly assigning experimental units to treatments?
15. Suppose you are presented with 24 experimental units and 6 treatments to accommodate. If you wanted to create a completly randomized design, how would you randomize? If you wanted to create a randomized complete block design, how would you randomize? What might you have to do if you could only find groups (blocks) of 4 homogeneous experimental units?
16. Look at example 14.11 on page 847 in the book. Suppose that we change the value of D, in this case the economically important difference in average yields, down to 12 pounds. What sample size would be needed to have an overall power for the F-test for equal group means of 0.80?