4. Explain how you might design a statistical test to examine the presence of a certificate-of-need law on hospital care expenditures.What would be your main hypothesis in this experiment?What would be the unit of analysis in your experiment?What variables would you specify on the right-hand side of the estimation equation to act as control variables?What would be your identification strategy to eliminate any concerns about reverse causation or a third variable affecting both the presence of a CON law and hospital care expenditures?