||This is the basic
strategy behind an experimental epidemiological study. To show that a treatment is
effective, the improvement rate in a treated group (T) should be greater than the
improvement rate in the untreated group (NT), and that the differences in rates should be
unlikely they are due to chance.
The control group (NT) should be similar to the
treatment group (T) in all characteristics associated with the expected outcome
(recovery), and should not receive the studied treatment. The control group may be
receiving the prevailing, or current standard of care, or a placebo.