Explain what is meant by the term placebo, and how a placebo would be utilised in a clinical trial of a novel pain relief medication

A placebo is a control method to account for perceived effects of taking a medication. This is because patients often report that they feel a difference from taking a medication, irrespective of whether it has had a biological effect. Therefore, a placebo accounts for any psychological biases within a study. In a clinical trial of a novel analgesic, a placebo would be used as a control to determine the extent of pain relief that is psychological. This could be implemented in a double-blind, repeated measures design whereby the experimenter randomly allocates the patient either the placebo or the drug on testing days, and then subsequently compares patient ratings of pain relief relative to a non-testing, negative control day. When this method is repeated across all patients in the study, this would determine the percentage of pain relief that is psychological, and irrespective of the pharmacological effects of the drug.