The scientists found no difference in the survival of people with minor depression in the treated or untreated groups.

The patients suffered less heart disease than an untreated group but, oddly enough, didn't live any longer.

"Then you can't justify having an untreated group."

We could then calculate the sample means within the treated and untreated groups of subjects, and compare these means to each other.

At the end of the study, the scientists found no difference between the treated and untreated groups.

After two weeks, 75.4 percent of the babies in the moxibustion group had turned, compared with 47.7 percent in the untreated group.

However, studies generally do not include an untreated group, so determining the actual size of the placebo effect, compared to totally untreated patients, is difficult.

New patients with the viral infection can only obtain the drug by enrolling in this study and thus facing a chance of being placed in the untreated group.

The simplest analysis was in example 2, where weighted estimates of the differences between treated and untreated groups were computed for pain and disability outcomes.

In our study, mean survival time was significantly longer in the ibuprofen-treated groups compared with the untreated group.