Suppose IQ scores were obtained from randomly selected twins

Suppose IQ scores were obtained from randomly selected

twinstwins.

For

20

such pairs of people, the linear correlation coefficient is

0.910

and the equation of the regression line is

ModifyingAbove y with caret equals 11.01 plus 0.91 xy=11.01+0.91x,

where x represents the IQ score of the

twin born firsttwin born first.

Also, the

20

x values have a mean of

100.2

and the

20

y values have a mean of

102.6.

What is the best predicted IQ of the

twin born secondtwin born second,

given that the

twin born firsttwin born first

has an IQ of

98?

Use a significance level of 0.05.

Solution

Suppose IQ scores were obtained from randomly selected twinstwins. For 20 such pairs of people, the linear correlation coefficient is 0.910 and the equation of the regression line is ModifyingAbove y with caret equals 11.01 plus 0.91 x y=11.01+0.91x, where x represents the IQ score of the twin born firsttwin born first. Also, the 20 x values have a mean of 100.2 and the 20 y values have a mean of

102.6. What is the best predicted IQ of the twin born secondtwin born second, given that the twin born firsttwin born first has an IQ of 98? Use a significance level of 0.05.

The regression line is

y=11.01+0.91x

when x=98,

y =11.01+0.91*98 = 100.19

Best predicted IQ =100.19