1. The main things to look for in scatterplots include all of the below except:

Question

1.     The main things to look for in scatterplots include all of the below except:

a.     Direction

b.     Form

c.     Strength

d.     Negative values

1.     The slope gets its sign from the ______________.

a.     covariance

b.     r-squared

c.     correlation

d.     standard deviation

1.     Least square lines are commonly called

a.     Regression lines

b.     Linear lines

c.     Statistical lines

2.     All of the following are conditions to check prior to regression except:

a.     Quantitative Variable Condition

b.     Linearity Condition

c.     Outlier Condition

d.     Overall Condition

1.     Correlation treats x and y

a.     Symmetrically

b.     Non-Symmetrically

c.     As outliers

d.     Cannot be determined

1.     An R-squared of 0.578 for the weight of a Samsung TV indicates

a.     57.8% of the variation in the weight of a Samsung TV is accounted for by some independent variable

b.     42.2% of the variation in the weight of a Samsung TV is accounted for by some independent variable

c.     Cannot be determined

2.     How big should R-squared be to determine a “good” regression?

a.     80%

b.     50%

c.     30%

d.     There is no value of R-squared that automatically determines a regression is “good”

Explanation / Answer

Ans 1- The main things to look for in scatterplots include all of the below except "Negative values".

Ans 2 - The slope gets its sign from the "correlation".If the correlation is positive, the scatterplot runs from lower left to upper right and the slope of the line is positive.

Ans 3 - Least square lines are commonly called as "Regression lines".The line of best fit is the line for which the sum of the squared residuals is smallest is called as the least squares line or regression lines.

Ans 4- All of the following are conditions to check prior to regression except "Overall Condition"

Quantitative Variables Condition: Correlation applies only to quantitative variables.

Linearity Condition: Correlation measures the strength only of the linear association.

  Outlier Condition: Unusual observations can distort the correlation.

Ans 5 - Correlation treats x and y "Symmetrically".The correlation of x with y is the same as the correlation of y with x.

Ans 6 - An R-squared of 0.578 for the weight of a Samsung TV indicates "57.8% of the variation in the weight of a Samsung TV is accounted for by some independent variable". r2 gives the fraction of the data’s variation accounted for by the model.r2 is called as “R squared”.

Ans 7- d is the correct option.There is no value of R-squared that automatically determines a regression is “good”. Data from scientific experiments often have R-sqared in the 80% to 90% range.Data from observational studies have an acceptable R-sqared in the 30% to 50% range.

Thanks

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