Concept explainers
In the descriptions of experiments given in Exercises 2.15–2.18, identify the important features of each design. Include as many of the components listed in Exercise 2.14 as needed to adequately describe the design.
2.17 In place of the design described in Exercise 2.16, make the following change. Within each hospital, the three treatments will be randomly assigned to the patients, with two patients in each ward receiving D1, two patients receiving D2, and two patients receiving the placebo.
2.14 The process engineer designed a study to evaluate the quality of plastic irrigation pipes. The study involved a total of 48 pipes; 24 pipes were randomly selected from each of the company’s two manufacturing plants. The pipes were heat-treated at one one of four temperatures (175, 200, 225, 250°F). The pipes were chemically treated with one of three types of hardeners (H1, H2, H3). The deviations from the nominal compressive strength were measured at five locations on each of the pipes.
Identify each of the following components of the experimental design.
- a. Factors
- b. Factor levels
- c. Blocks
- d. Experimental unit
- e. Measurement unit
- f. Replications
- g.
Covariates - h. Treatments
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An Introduction to Statistical Methods and Data Analysis
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