The determinants of interest rates

Macro-economic factors, the FED, Markets... Lots of things are you studying for homework?

Credit score

I agree with MsMewiththat. You need to have a good credit score to get lower interest rates.

Right but are we talking about personal rates or just rates in general. As this was an economics question and not personal finance I thought rates in general.

Your question needs to be refined. Are you asking about rates you pay on a loan or rates you get on a deposit? Try to give us an example to work with.