research topic

The research topic I'm considering is about minimum wage and the impact on the economy. I want to know if there can be a maximum wage, or no wage basis at all. Why does minimum wage vary with state? Is there a specific reason for this? The observation assignment did help me find my topic, but Professor Spencer helped me narrow it down. Minimum wage isn't enough for people to live off by. I think it should be raised or be based on how a person performs.