One hundred volunteers who suffer from severe depression are available for a study. Fifty are selected at random and are given a new drug that is thought to be particularly effective in treating severe depression. The other 50 are given an existing drug for treating severe depression. A psychiatrist evaluates the symptoms of all volunteers after 4 weeks in order to determine if there has been substantial improvement in the severity of the depression. In which situation would this study be double blind?

Question

1. If neither the volunteers nor the psychiatrist knew which treatment any person had received
2. If all volunteers were not allowed to see the psychiatrist nor was the psychiatrist allowed to see the volunteers during the session when the psychiatrist evaluated the severity of the depression
3. All of the above
4. If neither drug had any identifying marks on it

3?

Answer 1

@Anonymous, yes it would be #3, all of the above.

Answer 2

I believe it is #1

Answer 3

Agree with CodyJinks