When a patient failed to respond to prescribed medication, the doctor hypothesized that the dosage was insufficient  The doctor first advised doubling the dosage, but the patient' s symptoms remained  It was then learned that the patient regularly drank an herbal beverage that often inhibits the medication' s effect  The doctor then advised the patient to resume the initial dosage and stop drinking the beverage  The patient complied, but still showed no change  Finally, the doctor advised the patient to double the dosage and not drink the beverage  The patient' s symptoms disappeared
Hence, the doctor' s initial hypothesis was correct
They suggest that the beverage was not the only cause of the ineffectiveness of the prescribed dosage.