I have a project that asks As a researcher you will be considering the relationships between variables regularly.

I have a project that asks "As a researcher you will be considering the relationships between variables regularly. Linear correlation is the most basic relationship that may exist between two variables. This assignment will you give the opportunity to see how statistics can start to answer the research questions you will be faced with in your field of study.", I was wondering how I would find my two variables. Would I use a article that already has the information or would I find two seperate articles with the data needed. For instance I want to do correlation between the age of a person and the arrests for murder.