# Quantitative Statistical Assignment

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Question 1 The following data are IQ scores for 50 persons. (p. 44) 141 115 87 91 96 92 118 98 101 107 97 118 124 146 108 106 135 97 108 129 107 101 110 129 109 83 127 116 113 105 127 112 114 114 139 109 102 113 106 89 108 102 92 102 134 104 101 131 86 123 Construct a grouped frequency distribution, using an interval width (w) of 10. Note each interval of the group frequency distribution should begin with a multiple of the interval width. This means that you won’t begin with the lowest of the 50 scores given above. Solution N=50 W=10 Max Value-Min Value= 146-83=63 Number of classes=63/10=6.3. Approximately 7 classes Class Limits Class Boundaries Frequency (f) Cumulative frequency 80-89 79.5-89.5 4 4 90-99 89.5-99.5 7 11 100-109 99.5-109.5 17 28 110-119 109.5-119.5 10 38 120-129 119.5-129.5 6 44 130-139 129.5-139.5 4 48 140-149 139.5-149.5 2 50 Question 2. Which of these correlation coefficients indicates the strongest relationship? a. .55 b. .09 c. -.77 d. .10 Solution Correlation coefficients make it possible to evaluate the strength of association existing between two variables. The values of correlation coefficients usually range from -1 to 1. The strongest linear relationship is normally the one close to -1 or 1. In this case, it is quite apparent that the right answer is (c)-0.77. Question 3 In a dataset, the X-observations below tend to be associated with Y-observations above, which of correlation coefficients in Question 2 best reflects this relationship between X and Y? (Note = mean of all X scores and = mean of all Y scores) Solution This scenario is normally referred to as the maximum positive correlation, where r=1.0.The correlation coefficient in Question

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