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A barrier is

Chris would like to conduct a study on the effectiveness of a new substance-abuse treatment program. he has a sample of participants go through the program and he uses as a comparison group people who did not volunteer for the program but were eligible. chris has used a(n) design for his study.

How were the economies of the northern and southern states different? how ere they the same? what factors led them to develop differently?

Which of the following is a problem in the health care system of the united states? a. too many doctors in rural areas b. too many doctors who are general practitioners c. fraud d. costs that are too low