Some child-development researchers tabulated the amount of crying by 38 babies when they were 4 to 7 days old, and then measured each baby’s IQ at 3 years of age [20]. Plot the data in Table 9.9 on a scatter diagram and use least squares to estimate the regression line Y = α + βX + ε, where Y is IQ and X is cry count. Is the relationship statistically significant at the 5 percent level? If there is a positive, statistically significant relationship, does this mean that you should make your baby cry?

Table 9.9

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Cry Count IQ Cry Count IQ Cry Count IQ Cry Count IQ 9 103 13 162 17 94 22 135 9 119 14 106 17 141 22 157 10 87 15 112 18 109 23 103 10 109 15 114 18 109 23 113 12 94 15 133 18 112 27 108 12 97 16 100 19 103 30 155 12 103 16 106 19 120 31 135 12 119 16 118 20 90 33 159 12 120 16 124 20 132 13 104 16 136 21 114