# How to test if variables are jointly determined?

If I wanted to test, for example, if consumption growth and credit growth are jointly determined, and therefore justifying the use of instrumental variables, how would I go about this? Would running a Hausman test work?

For instance if I assumed the structural equations

        Consumption= a + b * income+ c * Credit + e

Credit growth= d + f * income + g * consumption + ... + v


How could a Hausman test be used?