Question

A value of r= .40 indicates that there is a       

a.    Strong positive relationship between x andy.

Strong negative relationship between x andy.

Weak positive relationship between x andy.

Weak negative relationship between x andy.

__________20.  Which of the following is nota property of r?                                           

         a.   r does not depend on the units of y or x.

         b.   r is always between 0 and 1.

         c.   r measures the strength of the linear relationship between x and y.

         d.    r does not depend on which of the two linear variables is labeled x.

__________21.  The proportion of variation explained by a linear relationship between x and yis      a.              b.                      c.                              d.

__________22.  In the equation of a straight line, ,            

         a.   a is the slope and b is the y-intercept.

         b.    yis the predictor variable and x is the response variable.

         c.    a is the y-intercept and b is the slope.

         d.    y is the independent variable and x is the dependent variable.

__________23.  A point is called an influential observation when                      

         a.   It has a large residual.

         b.   It has a small residual.

         c.   It plays a big role in determining the slope of the least squares line.

         d.   It should be transformed using a power transformation.

__________24.  When regressing yon x, yis called the

         a. response variable.                                  b.  independent variable.

         c. Predictor variable.                                  d.  Explanatory variable.

Answer 1

19. A value of r= .40 indicates that there is a:

Ans: c. :Weak positive relationship between x andy.

(A correlation of above 0.70 is generally considered strong. 0.40 implies weak relationship. Since it is a positive number, we can say there is weak positive relationship.)

20. Which of the following is not a property of r?

Ans: b. :r is always between 0 and 1.

(The correlation coefficient, r is always between -1 and +1. Negative values imply negative relationship (that is, one increases while the other decreases) and positive values imply positive relationship (that is, one increases while the other increases). Closer the |r| value is to 1, stronger is the relationship between the two variables)

21. The proportion of variation explained by a linear relationship between x and y is

Ans: No options given. The definition seems like that of R² (or r squared). R squared is the proportion of variation in y that is explained by the predictor variables. It is SSR / SST (SSR is sum squares regression, and SST is sum squares total.).

22. In the equation of a straight line,

Ans: c. a is the y-intercept and b is the slope.

(y=a+bx is the equation of a straight line, where a is the y-intercept and b is the slope of the line.)

23. A point is called an influential observation when

Ans: c. It plays a big role in determining the slope of the least squares line.

(An outlier is a point which has a large residual. An influential point is a point that plays a big role in determining the slope of the least squares line.)

24.  When regressing yon x, yis called the

Ans: a. response variable.

(y is the response variable or the dependent variable or the explained variable.)