Final answer:
The doctor will not be able to determine the effectiveness of the new medicine because not every patient tried the new medication.
Step-by-step explanation:
The true statement about the design of this experiment is: because the doctor did not have every patient try the new medication, the doctor will not be able to determine the effectiveness of the new medicine.
In order to accurately determine the effectiveness of a new medication, it is necessary to have a control group, which does not receive the new medication. In this case, the doctor only had patients who were already taking medication for cholesterol volunteer for the trial.
Without a control group, it is impossible to compare the effectiveness of the new medication to the previous medication or to determine the true impact of the new medication.