<prompt> Problem of bias is maximum withCoho studyCase studyCase control studyExperimental study  <response>: 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 