5. Have steps been taken to minimize bias?
It can be surprisingly difficult to avoid bias in clinical trials. For example, if patients know what treatment they received or if the investigators know which treatment a patient received, it may affect their impression of whether the patient improved–no matter how hard they try to avoid it. Therefore, it's important to ask what steps were taken to minimize bias. For example, was the trial “blinded” or “masked” so that neither the participants nor the investigators knew who was receiving which treatment? Researchers must always work to make sure that the study is objective and the results reflect the data accurately.