SOLUTION: Examining Relationships Question 3 Select one answer. 10 points If there is no relationship (linear or otherwise) between two quantitative variables as observed on a scatte

Question 1049220: Examining Relationships
Question 3
Select one answer.
10 points
If there is no relationship (linear or otherwise) between two quantitative variables as observed on a scatterplot, the value of the correlation coefficient, r, is likely to be which of the following?
� Closer to 1
� Closer to −1
� Closer to 0
� Either closer to −1 or 1
Question 4
Select one answer.
10 points
Using data from 100 hospitals, a correlation of r = 0.78 is found between the size of a hospital (measured in number of beds) and the average length of patient stays (measured in days). Which of the following is true?
� There is a pretty strong positive linear correlation between number of beds and length of hospital stay.
� �Severity of illness� is a possible lurking variable that is behind this relationship.
� Increasing hospital size must be the cause of longer patient stays.

Question 6
Select one answer.
10 points
Suppose the correlation between two variables (x, y) in a data set is determined to be r = 0.63, What must be true about the slope, b, of the least-squares line estimated for the same set of data?
� The slope b is always equal to the square of the correlation r.
� The slope will have the opposite sign as the correlation.
� The slope will have the same sign as the correlation.
� The slope will also be a value between −1 and 1.
Question 7
Select all that apply.
10 points
A study was done on the timeliness of flights categorized as either "on time" or "delayed" of two major airlines: StatsAir and AirMedian. Data were collected over a period of time from five major cities and it was found that StatsAir does better overall (i.e., has a smaller percentage of flights categorized as delayed). However, in each of the five cities separately, AirMedian does better (i.e., has a smaller percentage of flights categorized as delayed in each city).
Which of the following is correct? Check all that apply.
� This is an example of Simpson's paradox.
� "City" is a lurking variable in this example.
� This is an example of a negative association between variables.
Question 8
Select one answer.
10 points
A correlation of r = 0.85 is found between weekly sales of firewood and cough drops over a 1-year period. Which of the following is a correct interpretation of this correlation value?
� Temperature is a possible lurking variable that is behind this relationship.
� There is a pretty strong positive linear relationship between sales of firewood and cough drops.
� Fire must be the cause of coughing.

Answer by ikleyn(52790) (Show Source): You can put this solution on YOUR website!
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One question per post please.

It is the rule of this site.

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