<prompt> In a double blind clinical drug trial -Each patient receives a placeboEach patient receives both double treatmentThe patients do not know which treatment they are receivingThe patients do not know that they are in a drug trial  <response>: DOUBLE BLINDING: In a double-blind trial, the patients as well as the investigator are blinded i.e. they dont know who is receiving the study drug and who is receiving placebo. It removes subject investigator bias. MC binding seen. OTHER TYPES OF BLINDING: Single blinding : Subjects are not aware of treatment. Used to remove subject bias. Triple binding : Subject, investigator analyzer are not aware of treatment. Removes subject, investigator analyzer bias. It is best blinding. Open study : Complete absence of blinding. 