Observational Studies and Experiments

Question 1

In this experiment, the experimental units are the . The bakery testing the flours should create treatment groups, one group for each type of .

Revolt · Accepted Answer

C: baked goods

Question 2

In this experiment, the experimental units are the . The bakery testing the flours should create treatment groups, one group for each type of .

Revolt · Accepted Answer

B: new flour

Question 3

Why is randomization important?Select the statement that best answers the question.

Revolt · Accepted Answer

C: to ensure that all treatment groups are roughly equivalent regarding the variability within the experimental units

Question 4

Suppose we want to determine how long it takes on average for a typical adult to build four different styles of tables, which are referred to as A, B, C, and D. To create four treatment groups, the researcher begins by writing the name of each member of the population on a slip of paper. Next, the researcher puts all slips of paper into a hat and shuffles them well. Finally, the researcher draws slips of paper from the hat to determine the participants in the experiment. Identify the component missing from the researcher’s process.

Revolt · Accepted Answer

A: The researcher did not assign individuals to treatment groups.

Question 5

A company wants to test clear deck sealants for weather resistance. Three brands of sealants will be testedusing 60 pieces of decking wood. The company wants to create treatment groups of 20 pieces of wood each,and decide to randomize using slips of paper. Select all the approaches that would result in comparabletreatment groups.The numbers 1, 2, and 3 are each written on 20 slips of paper, and the slips areplaced in a hat and shaken well. The top piece of wood from a stack is selected and aslip of paper is drawn from the hat. That piece of wood is assigned to the group numberon the slip. The slip of paper is returned to the hat. This continues until all pieces of woodhave been assigned to a group.The numbers 1, 2, and 3 are written on three slips of paper, put into a hat, and shaken well. Aslip is drawn and the first 20 pieces of wood on the stack are assigned to the group number on theslip. Another slip is drawn and the next 20 pieces of wood are assigned to that group. The remaining

Revolt · Accepted Answer

C: Each piece of decking wood is assigned a number from 1 to 60. The numbers 1–60 are written on slips of paper and placed in a hat and shaken well. Twenty slips are drawn, shakingthe hat after each slip of paper is drawn, and the pieces of wood corresponding to those numbersare placed in group 1. Twenty more slips are drawn in the same way, and the pieces of woodcorresponding to those numbers are placed in group 2. The pieces of wood corresponding to thenumbers on the remaining slips are placed in group 3.; D: The numbers 1, 2, and 3 are each written on 20 slips of paper (20 for each number) and the slips are placed in a hat and shaken well. The top piece of wood from a stack is selected,and a slip of paper is drawn from the hat. That piece of wood is assigned to the group number onthe slip. The slip of paper is not returned to the hat. This continues until all pieces ofwood have been assigned to a group.

Question 6

A company wants to test clear deck sealants for weather resistance. Three brands of sealants will be tested using nine pieces of decking wood. The company wants to randomly assign the pieces of wood to the treatment groups using a table of random digits to produce three equal-sized groups suitable for comparison. Select the appropriate design.

Revolt · Accepted Answer

B: Number each piece of wood with a digit from 1–9. Read from left to right, looking at one digit at a time on a random number table to identify 9 unique one-digit numbers from 1–9. Assign the wood labeled with the first 3 numbers to sealant 1, the wood labeled with the next 3 numbers to sealant 2, and the remaining wood to sealant 3.

Question 7

The subjects in this study should be numbered using numbers from . Using a table of random digits, the researcher should work from left to right starting with the first row and first column to select numbers, select values that are in the correct range, and skip repeating numbers. The subjects whose numbers correspond to the randomly generated numbers are assigned to group A. The remaining subjects are assigned to group B.

Revolt · Accepted Answer

B: two-digit

Question 8

The subjects in this study should be numbered using numbers from . Using a table of random digits, the researcher should work from left to right starting with the first row and first column to select numbers, select values that are in the correct range, and skip repeating numbers. The subjects whose numbers correspond to the randomly generated numbers are assigned to group A. The remaining subjects are assigned to group B.

Revolt · Accepted Answer

B: 01 – 60

Question 9

In this experiment, the experimental units are the . The bakery testing the flours should create treatment groups, one group for each type of .

Revolt · Accepted Answer

C: 3

Question 10

The subjects in this study should be numbered using numbers from . Using a table of random digits, the researcher should work from left to right starting with the first row and first column to select numbers, select values that are in the correct range, and skip repeating numbers. The subjects whose numbers correspond to the randomly generated numbers are assigned to group A. The remaining subjects are assigned to group B.

Revolt · Accepted Answer

A: 30

Observational Studies and Experiments Answers

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