Chapter 4.2, Problem 101E

To determine

To explain do identical twins living in low-income homes tend to have lower IQs later in life than their twins who live in high-income homes.

Answer to Problem 101E

There is evidence that identical twins living in low-income homes tend to have lower IQs later in life than their twins who live in high-income homes.

Explanation of Solution

In the question, it is given that a researcher studied a group of identical twins who had been separated and adopted at birth. Thus, now, we will calculate the mean for both the twins as:

  $\begin{array}{l}{\overline{x}}_A=\frac{120+99+\mathrm{....}+113+100}{12}\\ =103.6667\\ {\overline{x}}_B=\frac{128+104+\mathrm{....}+114+112}{12}\\ =109.5\end{array}$

We then note that the difference in IQ scores is about five points but this difference could be due to chance since the sample size is only $12$ . Thus we can conclude that there is no statistically significant proof that identical twins living in low-income homes tend to have lower IQs later in life than their twins who live in high-income homes.