# How can I test possible reasons for the relationship between income and handedness?

For a project, I am trying to determine what accounts for the difference in income between left handed people and right handed people. (For example, whether it is only among males, or only in a certain field, education level etc.)

For independent variables, I will be looking at:

• handedness
• education level
• sex
• job category (jobs will be divided into 3-4 categories)

For the dependent variable, I simply have income.

My theory is that left handed people tend to pick jobs which are lower paying, which is why they have on average a lower income than right handed people. So what kinds of statistical tests could I use to show the following relationship is statistically likely:

left handed --> lower paying job --> lower income

• The question of whether it is only among males, eg, is a question of moderation. You can test that with an interaction term. The causal chain at the bottom is a model of mediation. Testing that is more complicated. – gung May 30 '15 at 3:48
• this is basically what I was looking for. Thanks! – Bobby Jones May 30 '15 at 4:20

You list several questions, and they are different types of questions. For example, the question of whether it is only among males, is a question of moderation. You can test that with an interaction term. That is, you would create a new variable as the product of your indicator variable for sex and your indicator for handedness.