Suppose IQ scores were obtained from randomly selected twins. For 20 such pairs

Question

Suppose IQ scores were obtained from randomly selected twins. For 20 such pairs of people, the linear correlation coefficient is 0.919 and the equation of the regression line is y = 8.15 + 0.93x, where x represents the IQ score of the twin born second. Also, the 20 x values have a mean of 99.03 and the 20 y values have a mean of 100.15. What is the best predicted IQ of the twin born first, given that the twin born second has an IQ of 94? Use a significance level of 0.05. First, check to see if there is a linear correlation that justifies using the regression equation to predict values What are the critical values of the correlation coefficient for a sample size of 20 and a level of significance of 0.05? r = plusminus (Round to three decimal places as needed.)

Explanation / Answer

critical value for (n-2=18) degree of freedom ; r =-/+ 0.444

predicted value =8.15+0.93*94 =95.57

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