Example: Let's say you have selected wealth inequality and health as your topic. How does wealth inequality affect health? Think about:
For example, you might think wealth inequality is a problem because it creates unequal access to health care. Then, the problem is defined as the difference in access to health care between the wealthy and those in poverty.
OR, You might think wealth inequality is a problem because of the difference in children's health. Then, the problem is defined as the difference in children's health as a result of wealth inequality.
OR You might think wealth inequality is a problem because of the difference in mortality rate and life expectancy. Then, the problem is defined as the effect of wealth inequality on life expectancy and mortality.
There are many possibilities!
When writing your paper, be sure to include information on causes and effects of your defined problem.