Stats Review

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11. A coefficient of correlation r close to 0 (say 0.08) shows that the relationship btwn 2 variables is quite weak

True

False

12. In order to visualize the form of the regression equation, we can draw a scatter diagram

True

False

13. An economist is interested in predicting the unemployment rate based on gross domestic product. since the economist is interested in predicting unemployment, the independent variable is gross domestic product

True

False

14. The purpose of correlation analysis is to find how strong the relationship is between 2 variables

True

False

15. Coefficients of -0.91 and +0.91 have equal strength

True

False

16. A correlation coefficient of -1 or +1 indicates perfect correlation

True

False

17. The regression equation is used to estimate a value of the dependent variable y based on a selected value of the independent variable x

True

False

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19. A line found using the least squares principle is the best-fitting line because the sum of the squares of the vertical deviations btwn the actual and estimated values is minimized

True

False

20. If all the plots on a scatter diagram lie on a straight line, what is the standard error of estimate

-1

1

0

Infinity

None

21. The coefficient of determination can only be positive

True

False

22. In regression analysis, the predicted value of y' rarely agrees exactly with the actual y value, i.e. we expect some prediction error

True

False

23. Which value of r indicates a stronger correlation than -.4?

-.3

-.5

0

.3

None of the above

24. In the regression equation, y'=a + bx, what does the letter b represent?

Y intercept

Slope

Any value of the independent variable that is selected

Value of y when x=0

None of the above

25. If the correlation btwn 2 variables is close to one, the association is

Strong

Moderate

Weak

None

26. Which value of r indicates a stronger correlation than .4?

-.3

-.5

.38

0

None of the above

27. If the coefficient of correlation is -0.9, the coefficient of determination is -0.81

True

False

28. Which of the following is true about the standard error of estimate

Measure the accuracy of the prediction

Based on squared vertical deviations between y and y'

Cant be negative

All

None

29. In the regression equation, y'=a + bx, what does the letter a represent?

Y intercept

Slope

Any value of the independent variable that is selected

None of the above

30. Given the following five pts: (-2, 0), (-1, 0), (0,1), (1,1) and (2,3)
what is the y intercept

0

.7

1

1.5

None

31. A statistics student made the following grades on 5 tests: 84, 78,88,78 and 72. whats the mean?

78

80

72

84

88

32. A commuter travels many miles to work each morning. she has timed this trip 5 times during the last month. the time (in min) required to make this trip was 44, 39, 41, 35, and 41. the mean time required for this trip was 40 min. what is the variance for this sample data?

8.8

11

0

3

-2

33. What does a coefficient of correlation of .7 infer?

Almost no correlation because .7 is close to 1

70% of the variation in one variable is explained by the other

Coefficient of determination is 0.49

Coefficient of nondetermination is .3

None of the above

34. The mean life of a particular brand of light bulb is 1000 hrs and the standard deviation is 50 hrs. we can conclude that at least 75% of this brand of bulbs will last between

900 and 1100 hrs

950 and 1050

850 and 1150

800 and 1200

1050 and 1250

35. Consider the following stem and leaf plotstem leaf1 0,2,5,72 2,3,4,83 0,4,6,6,94 5,8,8,95 2,7,8
suppose that a frequency distribution was developed from this, and there were 5 classes (10 under 20, 20 under 30, etc) what is the cumulative frequency for the 30 under 40 class interval?

5

9

13

14

18

36. Using data from a group to generalize to a larger group involves the use of __

Descriptive statistics

Inferential statistics

Population derivation

Sample persuasion

Relative level data

37. Liz manages a portfolio of 250 common stocks. her staff compiled the following performance stats for the 2 new stocks
stock mean standard deviationproducts inc 15% 5%board inc 20% 5%
the coefficient of variation for products inc is __

300%

100%

33%

5%

23%

38. The strength of the correlation btwn 2 variables depends on the sign of the coefficient of correlation

True

False

39. Which of the following statements regarding the coefficient of correlation is true?

It ranges from -1 to +1 inclusive

It measures the strength of the relationship btwn 2 variables

A value of 0 indicates 2 variables are not related

All of the above

None of the above

40. The coefficient of determination is found by taking the square root of the coefficient of correlation

True

False

41. If the correlation coefficient btwn 2 variables = 0, what can be said of the variables x and y?

Not related

Dependent on each other

Highly related

All of the above are correct

None of the above are correct

42. Which of the following is not a legitimate probability value?

.67

15/16

.23

2/3

-.28

43. If a scatter diagram shows very little scatter about a straight line drawn through the plots, it indicates a rather weak relationship

True

False

44. The number of phone calls arriving at a switchboard each hr has been recorded, and the following frequency distribution has been developed
class interval frequency20 under 40 3040 under 60 45 60 under 80 8080 under 100 45
what is the cumulative frequency of the third class?

80

.4

155

75

105

45. Which value of r indicates a stronger correlation than .25?

-.3

-.5

.3

All of the above

None of the above

46. commuter travels many miles to work each morning. she has timed this trip 5 times during the last month. the time (in min) required to make this trip was 44, 39, 41, 35, and 41. the mean time required for this trip was 40 min. what is the standard deviation for this sample data?

3.32

2.97

1.73

11

-1.4

47. Given the following five pts: (-2, 0), (-1, 0), (0,1), (1,1) and (2,3)
what is the slope of the line?

0

.5

.6

.7

None

48. A business is attempting to find the best small town in the US in which to relocate. as part of the investigation, the elevations of all small towns in the US are researched. some towns are located high in the rockies with elevations over 8000 feet. there are even some towns located in the south central valley of california with elevations below sea level. these elevations can best be described as which level of data

Interval

Ordinal

Nominal

Ratio

Relative

49. Consider the relative frequency distribution given below
class interval relative frequency20 under 40 .240 under 60 .360 under 80 .480 under100 .1

90

80

.9

54

100

50. What is the standard error of the estimate?

0

.135

.367

.606

None

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Stats Review

1. What is the range of values that the coefficient of determination can assume? __ and ___

2.

What first name or nickname would you like us to use?

2. A financial advisor is interested in predicting bond yield based on bond term, ie 1 yr, 2yrs, etc. what is the dependent variable?

3. If the value of r is -.96, what does this indicate about the dependent variable as the independent variable increases

4. Perfect correlation means that the scatter diagram will appear as a ______

5. If the dependent variable is measured in dollars, in what units is the standard error of estimate measured?

6. The following table shows the number of workdays absent based on the length of employment in years# of workdays absent 2 3 3 5 7 7 8length of emplmnt (yrs) 5 6 9 4 2 2 0What is the independent variable (x)?

7. The following table shows the number of workdays absent based on the length of employment in years# of workdays absent 2 3 3 5 7 7 8length of emplmnt (yrs) 5 6 9 4 2 2 0what is the dependent variable (y)?

8. The following table shows the number of workdays absent based on the length of employment in years# of workdays absent 2 3 3 5 7 7 8length of emplmnt (yrs) 5 6 9 4 2 2 0what is the slope of the linear equation?

9. The following table shows the number of workdays absent based on the length of employment in years# of workdays absent 2 3 3 5 7 7 8length of emplmnt (yrs) 5 6 9 4 2 2 0what is the y intercept of the linear equation?

10. The relationship btwn interest rates as a percent (x) and housing starts (y) is given by the linear equation y'=4094-269xwhat will be the # of housing starts if the interest rate is 8.25%?

11. A coefficient of correlation r close to 0 (say 0.08) shows that the relationship btwn 2 variables is quite weak

12. In order to visualize the form of the regression equation, we can draw a scatter diagram

13. An economist is interested in predicting the unemployment rate based on gross domestic product. since the economist is interested in predicting unemployment, the independent variable is gross domestic product

14. The purpose of correlation analysis is to find how strong the relationship is between 2 variables

15. Coefficients of -0.91 and +0.91 have equal strength

16. A correlation coefficient of -1 or +1 indicates perfect correlation

17. The regression equation is used to estimate a value of the dependent variable y based on a selected value of the independent variable x

18. If we are studying the relationship btwn high school performance and college performance, and want to predict college performance, high school performance is the indy or dependy variable?

19. A line found using the least squares principle is the best-fitting line because the sum of the squares of the vertical deviations btwn the actual and estimated values is minimized

20. If all the plots on a scatter diagram lie on a straight line, what is the standard error of estimate

21. The coefficient of determination can only be positive

22. In regression analysis, the predicted value of y' rarely agrees exactly with the actual y value, i.e. we expect some prediction error

23. Which value of r indicates a stronger correlation than -.4?

24. In the regression equation, y'=a + bx, what does the letter b represent?

25. If the correlation btwn 2 variables is close to one, the association is

26. Which value of r indicates a stronger correlation than .4?

27. If the coefficient of correlation is -0.9, the coefficient of determination is -0.81

28. Which of the following is true about the standard error of estimate

29. In the regression equation, y'=a + bx, what does the letter a represent?

30. Given the following five pts: (-2, 0), (-1, 0), (0,1), (1,1) and (2,3)what is the y intercept

31. A statistics student made the following grades on 5 tests: 84, 78,88,78 and 72. whats the mean?

32. A commuter travels many miles to work each morning. she has timed this trip 5 times during the last month. the time (in min) required to make this trip was 44, 39, 41, 35, and 41. the mean time required for this trip was 40 min. what is the variance for this sample data?

33. What does a coefficient of correlation of .7 infer?

34. The mean life of a particular brand of light bulb is 1000 hrs and the standard deviation is 50 hrs. we can conclude that at least 75% of this brand of bulbs will last between

35. Consider the following stem and leaf plotstem leaf1 0,2,5,72 2,3,4,83 0,4,6,6,94 5,8,8,95 2,7,8suppose that a frequency distribution was developed from this, and there were 5 classes (10 under 20, 20 under 30, etc) what is the cumulative frequency for the 30 under 40 class interval?

36. Using data from a group to generalize to a larger group involves the use of __

37. Liz manages a portfolio of 250 common stocks. her staff compiled the following performance stats for the 2 new stocksstock mean standard deviationproducts inc 15% 5%board inc 20% 5%the coefficient of variation for products inc is __

38. The strength of the correlation btwn 2 variables depends on the sign of the coefficient of correlation

39. Which of the following statements regarding the coefficient of correlation is true?

40. The coefficient of determination is found by taking the square root of the coefficient of correlation

41. If the correlation coefficient btwn 2 variables = 0, what can be said of the variables x and y?

42. Which of the following is not a legitimate probability value?

43. If a scatter diagram shows very little scatter about a straight line drawn through the plots, it indicates a rather weak relationship

44. The number of phone calls arriving at a switchboard each hr has been recorded, and the following frequency distribution has been developedclass interval frequency20 under 40 3040 under 60 45 60 under 80 8080 under 100 45what is the cumulative frequency of the third class?

45. Which value of r indicates a stronger correlation than .25?

46. commuter travels many miles to work each morning. she has timed this trip 5 times during the last month. the time (in min) required to make this trip was 44, 39, 41, 35, and 41. the mean time required for this trip was 40 min. what is the standard deviation for this sample data?

47. Given the following five pts: (-2, 0), (-1, 0), (0,1), (1,1) and (2,3)what is the slope of the line?

49. Consider the relative frequency distribution given belowclass interval relative frequency20 under 40 .240 under 60 .360 under 80 .480 under100 .1

50. What is the standard error of the estimate?

51. If the correlation btwn sales and advertising is 0.6, what percent of the variation in sales can be measured?

52. The following table shows the number of workdays absent based on the length of employment in years# of workdays absent 2 3 3 5 7 7 8length of emplmnt (yrs) 5 6 9 4 2 2 0what is the least squares equation for the data?

53. What is the standard error of estimate?

54. The relationship btwn interest rates as a percent (x) and housing starts (y) is given by the linear equation y'=4094-269xat what interest rate will there be no permits for housing starts?

55. The relationship btwn interest rates as a percent (x) and housing starts (y) is given by the linear equation y'=4094-269xwhat happens to housing starts as interest rates fall?

1. What is the range of values that the coefficient of determination can assume? and _

6. The following table shows the number of workdays absent based on the length of employment in years
# of workdays absent 2 3 3 5 7 7 8length of emplmnt (yrs) 5 6 9 4 2 2 0
What is the independent variable (x)?

7. The following table shows the number of workdays absent based on the length of employment in years
# of workdays absent 2 3 3 5 7 7 8length of emplmnt (yrs) 5 6 9 4 2 2 0
what is the dependent variable (y)?

8. The following table shows the number of workdays absent based on the length of employment in years
# of workdays absent 2 3 3 5 7 7 8length of emplmnt (yrs) 5 6 9 4 2 2 0
what is the slope of the linear equation?

9. The following table shows the number of workdays absent based on the length of employment in years
# of workdays absent 2 3 3 5 7 7 8length of emplmnt (yrs) 5 6 9 4 2 2 0
what is the y intercept of the linear equation?

10. The relationship btwn interest rates as a percent (x) and housing starts (y) is given by the linear equation y'=4094-269x
what will be the # of housing starts if the interest rate is 8.25%?

30. Given the following five pts: (-2, 0), (-1, 0), (0,1), (1,1) and (2,3)
what is the y intercept

35. Consider the following stem and leaf plotstem leaf1 0,2,5,72 2,3,4,83 0,4,6,6,94 5,8,8,95 2,7,8
suppose that a frequency distribution was developed from this, and there were 5 classes (10 under 20, 20 under 30, etc) what is the cumulative frequency for the 30 under 40 class interval?

37. Liz manages a portfolio of 250 common stocks. her staff compiled the following performance stats for the 2 new stocks
stock mean standard deviationproducts inc 15% 5%board inc 20% 5%
the coefficient of variation for products inc is __

44. The number of phone calls arriving at a switchboard each hr has been recorded, and the following frequency distribution has been developed
class interval frequency20 under 40 3040 under 60 45 60 under 80 8080 under 100 45
what is the cumulative frequency of the third class?

47. Given the following five pts: (-2, 0), (-1, 0), (0,1), (1,1) and (2,3)
what is the slope of the line?

49. Consider the relative frequency distribution given below
class interval relative frequency20 under 40 .240 under 60 .360 under 80 .480 under100 .1

52. The following table shows the number of workdays absent based on the length of employment in years
# of workdays absent 2 3 3 5 7 7 8length of emplmnt (yrs) 5 6 9 4 2 2 0
what is the least squares equation for the data?

54. The relationship btwn interest rates as a percent (x) and housing starts (y) is given by the linear equation y'=4094-269x
at what interest rate will there be no permits for housing starts?

55. The relationship btwn interest rates as a percent (x) and housing starts (y) is given by the linear equation y'=4094-269x

what happens to housing starts as interest rates fall?