NOTE: There is not any data for these questions, so no data analysis required.Answer all questions based on the given scenarios.

Experimental Unit: The physical entity to which the treatment is randomly assigned or the subject that is randomly selected from one of the treatment populations (page 35 in our text).

Question 1

Scenario

The Agricultural Experiment Station of a university tested two different herbicides and their effects on crop yield.From 90 acres set aside for the experiment, the station used herbicide 1 on a random sample of 30 one acre plots and herbicide 2 on a second random sample of 30 one acre plots; they used the remaining 30 one acre plots as a control.The yields (in bushels per acre) were recorded.

(a)What is the treatment structure?

(b)List all treatments:

(c)What is the experimental unit?

(d)What is the design structure?

Question 2

Scenario

In many integrated circuit manufacturing steps, wafers are completely coated with a layer of material such as silicon dioxide or a metal.The unwanted material is then selectively removed by etching through a mask, thereby creating circuit patterns, electrical interconnects, and areas in which diffusions or metal depositions are to be made.A plasma etching process is widely used for this operation. Energy to the etching tool is supplied by a radio-frequency (RF) generator causing plasma to be generated in the gap between the electrodes.

An engineer is interested in investigating the relationship between the RF power setting and the etch rate for a typical single-wafer etching tool.The objective of this experiment is to investigate the effect of RF power on mean etch rates. Four levels of RF power will be tested: 160, 180, 200, and 220 Watts and five wafers will be etched for each level of RF power. There are 20 identical wafers available for this experiment.All other variables that could potentially affect etching rate will be held constant for the duration of this experiment.

Since only one wafer can be etched at a time, it is necessary to randomize the order of the 20 runs.The randomized test sequence is necessary to prevent the effects of unknown nuisance variables from contaminating the results.

(a)What is the treatment structure?

(b)List all treatments:

(c)What is the experimental unit?

(d)What is the design structure?