Question

According to the summary, the researchers measured kids’ IQ, math skills, reading skills, and SES (socioeconomic status) at age 7 and then measured their income at age 42. They found that: “How much money the people made at midlife was predicted by math ability at age seven. The other factors may have helped them on the path to success, but even when those were controlled for, the association between basic math and reading skills and future socioeconomic status remained, and remained significant . . .” Do you notice how this description uses the key phrase, “even when those were controlled for”? This should signal to you that the researchers used multiple regression in their design!

1. Does this study address temporal precedence - why or why not?

2. Suppose a critic reads this article and says, "I don't think that it's math skills—I think it's IQ. Smarter people have better math skills in childhood and smarter people earn more money in adulthood, that's all." In this study, is IQ a potential third variable that could explain the association between math skills and future income?

3. Now suppose that a critic suggests that school quality might be a third variable. Kids who go to higher-quality schools had better math skills and kids who went to higher-quality schools also went on to earn more money in adulthood. In this study, is school quality a potential third variable that could have explain the association between math skills and future income?

Answer 1

1) Temporal precedence is when one establishes a cause effect relationship. i.e. One variable leads to or causes a reaction in another variable. This study is largely a co-relational study. It does not address temporal precedence. A co-relational study can never imply causation. It merely suggests that a relationship between variables exists. As in this study they studied if there is a relationship between IQ, math skills, reading skills, SES (socioeconomic status) and income levels later in life. It was found that the highest co-relation was for math skills at age 7 and income later in life. This does not imply causation in any way.

2) IQ could be a potential overall variable. Math’s skills are part of IQ. So higher Math skills would boost the IQ score. Hence, it could possibly be interpreted as the overall factor in this study. Researchers could further sort the data and see the extent of correlation between IQ and income and Math’s scores and income later in life.

3) School quality could be a potential third variable. It has been shown by numerous research studies that better schools and teachers leads to higher IQ scores. When overall teaching and quality of education is better it is but inevitable to lead to better grades especially in Mathematics. Hence, there is potential in saying that the third variable is school quality which is related to better math scores which is co-related with higher income later in life. Researchers could further sort the data and see the extent of correlation between school quality and income and Math’s scores and income later in life and investigate the relation of the third variable of school quality.