Problem of bias is maximum with: (A) Coho study, (B) Case study, (C) Case control study, (D) Experimental study
Answer is C. Bias is any systemic error in the determination of the association between exposure and disease. The relative risk may increase or decrease as a result of the bias it reflects some type of no compatibility between the study and control groups. The possibility of bias must be considered when evaluating a possible cause and effect relationship. (refer pgno 73, park 23rd edition)