A drug may not be given equally to all patients.
"Vancomycin for your mother, metronidazole for your mother-in-lw" (Read, 2007)
Prescription bias can occur when a drug is prescribed:
(1) only for a certain disease severity
(2) only to a subset of patients based on sex, education or insurance
(3) only to a subset of patients who may be able to use or not use a drug or device (such as an inhaler) correctly
Prescription bias may also extend to the dose and route of administration.
