Statistical Help

Question

Suppose IQ scores were obtained from randomly selected siblings. For 20 such pairs of people, the linear correlation coefficient is 0.887 and the equation of the regression line is y = -2.86 + -2.86 + 1.03_x where x represents the IQ score of the younger child.  Also the 20 x values have a mean of 101.73 and the 20 y values have a mean of 101.8.  What is the best predicted IQ of the older child, given that the younger child has an IQ of 108?

Answer 1

Hello, thank you for taking the time to post your question!

When you are using a regression equation to get a predicted value you just want to plug in the value of x into the equation. In this case that would mean plugging in x = 108  into the equation y = -2.86 + 1.03x

That yields

y = -2.86 + 1.03(108)

y = -2.86 + 111.24

y = 108.38

so the best predicted IQ of the older child based on the underlying regression equation is 108.38

I hope that helps! Feel free to reach out if you have any questions beyond that or want to go over how you might go about writing this :)