Final answer:
In studying the effect of education on income, the years of education is the independent variable and income is the dependent variable. Various statistical methods are employed to analyze the data and determine the relationship between these variables.
Step-by-step explanation:
When analyzing the relationship between years of education and income, the independent variable is the years of education since this is the determining factor you manipulate or categorize to observe how it affects income. The dependent variable is income because it is the outcome or effect that is being studied for change in response to changes in the independent variable.
In social research, independent variables are thought to influence or cause changes in dependent variables. For instance, how gender (the independent variable) affects the rate of income (the dependent variable), or how one's religion (the independent variable) affects family size (the dependent variable).
To examine the relationship between these variables, one would typically collect data from a sample, such as the 600 thirty-year-olds mentioned, and use statistical methods like a test of independence, scatter plots, least-squares line calculations, and correlation coefficients to determine the nature and strength of the relationship.