CHAPTER 3Describing Data: Numerical Multiple-Choice Questions1 . A s c a t t e r p l o t c a n i l l u s t r a t e a l l o f t h e f o l l o w i n g e x c e p t : A) The median of each of the variables.B) The range of each of the variables.C) An indication of outliers.D) Patterns of values.A N S W E R : A2 . F o r t h e f o l l o w i n g s c a t t e r p l o t , w h a t w o u l d b e y o u r b e s t e s t i m a t e o f t h e c o r r e l a t i o n coefficient?A ) - 0 . 8 B ) - 1 . 0 C ) - 0 . 3D)0.0A N S W E R : A39010203040501 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5

Chapter 33 . F o r t h e f o l l o w i n g s c a t t e r p l o t , w h a t w o u l d b e y o u r b e s t e s t i m a t e o f t h e c o r r e l a t i o n coefficient?A ) 1 . 0 B ) 0 . 8 C ) 0 . 3D)0.0A N S W E R : B4 . C a l c u l a t e t h e c o r r e l a t i o n f o r t h e f o l l o w i n g (X ,Y ) data: (53, 37), (34, 26), (10, 29), (63, 55),(28, 36), (58, 48), (28, 41), (50, 42), (39, 21), and (35, 46).A)0.710B ) 1 0 0 . 6C)0.670D)

0.590A N S W E R : D5. Suppose that we are interested in exploring the determinants of successful high schools.One possible measure of success might be the percentage of students who go on tocollege. The teachers’ union argues that there should be a relationship between thea v e r a g e t e a c h e r s ’ s a l a r y a n d h i g h s c h o o l s u c c e s s . T h e f o l l o w i n g e q u a t i o n o f t h e regression line is obtained: “%of students going on to college= 1 3 + 0 .001AverageTeachers’ Salary” Which of the following statements is true?A)I n c r e a s e % o f s t u d e n t s g o i n g o n t o c o l l e g e b y 0 . 0 0 1 p e r c e n t , w e w o u l d e x p e c t average teacher’s salary to increase by one dollar.B)Increase % of students going on to college by one percent, we would expect averageteacher’s salary to increase by 0.001 dollar.C)Increase teacher’s average salary by 0.001 dollar, we would expect % of studentsgoing on to college to increase by one percent.D)Increase average teacher’s salary by one dollar, we would expect % of studentsgoing on to college to increase by 0.001 percent.A N S W E R : D400204060803 0 4 0 5 0 6 0 7 0 8 0

Describing Data: Numerical

6. Suppose that we are interested in exploring the determinants of successful high schools.One possible measure of success might be the percentage of students who go on tocollege. The teachers’ union argues that there should be a relationship between theaverage teachers’ salary and high school success. After running a regression of thepercentage of students going on to college and average teachers’ salary, it is pointed outthat one school has a large negative residual. Which of the following is true?A) This school has very low values for both variables.B) This school has very high values for both variables.C) This school performed much worse than expected.D) This school performed much better than expected.A N S W E R : C7. Which of the following statements is true about correlation coefficient and covariance?A)The covariance is the preferred measure of the relationship between two variablessince it is generally larger than the correlation coefficient.B)The correlation coefficient is a preferred measure of the relationship between twovariables since its calculation is easier than the covariance.C) The covariance is a standardized measure of the relationship between variables.D)The correlation coefficient is the preferred measure of the relation between variablessince it is a standardized measure.A N S W E R : C8. Suppose we were to run a linear regression using the data in the following scatter plot.What are the most reasonable values for they -intercept0band the slope1b?A)0b= 0 and1b= 1B)0b= 25 and

1b= 2.5C)0b= -25 and1b= -2.5D)0b= 0 and1b= -1A N S W E R : B9 . W h i c h o f t h e f o l l o w i n g s t a t e m e n t s i s t r u e ?A)The correlation coefficient is always greater than the covariance.B)The covariance is always greater than the correlation coefficient.C)The covariance may be equal to the correlation coefficient.D)Neither the covariance nor the correlation coefficient can be equal to zero.A N S W E R : C410204060801001200 1 0 2 0 3 0 4 0 5 0