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The two-way table summarizes data from an experiment comparing the effectiveness of three different diets (A, B, and C) on weight loss. Researchers randomly assigned 300volunteer subjects to the three diets. The response variable was whether each subject lost weight over a 1-year period.

a. Suppose we randomly select one of the subjects from the experiment. Show that the events 鈥淒iet B鈥 and 鈥淟ost weight鈥 are independent.

b. Copy and complete the table so that there is no association between type of diet and whether a subject lost weight.

c. Copy and complete the table so that there is an association between type of diet and whether a subject lost weight.

Short Answer

Expert verified

Part a. The events 鈥渄iet B鈥 and 鈥淟ose weight鈥 are independent.

Part b. Two-way table

Diet



ABCTotal
Lose weightYes546066180

No36
40
44
120

Total90
100
110
300

Part c. Two 鈥 way table:

Diet



ABCTotal
Lose weightYes606060180

No30
40
50
120

Total90
100
110
300

Step by step solution

01

Part a. Step 1. Given information

Two 鈥 way table comparing the effectiveness of three different diets (A, B, and C) on weight loss:

02

Part a. Step 2. Explanation

The two events are independent, if the probability of occurrence of one event does not affect the probability of occurrence of other event.

For the events 鈥淒iet B鈥 and 鈥淟ose weight鈥 to be independent,

The product of row total and column total, divided by the table total should be equal to the count in the table.

Totalcount"Yes"Totalcount"B"Tabletotalcount=180100300=1803=60

In the table, we can see that the count in row 鈥淵es鈥 and column 鈥淏鈥 is already 60.

Thus,

The events 鈥淒iet B鈥 and 鈥淟ose weight鈥 are independent.

03

Part b. Step 1. Explanation

Two events are independent, when the probability of occurrence of one event does not affect the probability of occurrence of other event.

Then

The counts will be the product of the row total and the column total, divided by the table total provided in the bottom left corner of the table.

Calculate the counts in the two 鈥 way table:

Diet



ABCTotal
Lose weightYes9018030060110180300180

No90120300
40
110120300
120

Total90
100
110
300

Thus,

The two 鈥 way table becomes:

Diet



ABCTotal
Lose weight
Yes54role="math" localid="1664867620776" 60
66
180

No36
role="math" localid="1664867626081" 40
44
120

Total90
100
110
300
04

Part c. Step 1. Explanation

For two 鈥 way table, where an association exists between type of diet and whether a subject lost weight.

In this part, the count for column 鈥淎鈥 and row 鈥淵es鈥 should be different from Part (b).

Suppose, if we choose the count 60 for column 鈥淎鈥 and row 鈥淵es鈥 instead of 54 (in Part (b)).

Then

Put 60 in the column 鈥淎鈥 and the row 鈥淵es鈥.

And

Put the remaining counts according to the total counts of the rows and columns.

Thus,

The two 鈥 way table becomes:

Diet



ABCTotal
Lose weight
Yes6060
60
180

No30
40
50
120

Total90
100
110
300

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