Does St. John's wort have a significant effect in treating major depression? A study looked at 340 adult outpatients suffering from major depression as measured by their HAM-D score, randomly assigning each subject to either a placebo, St. John's wort, or a second active treatment for comparison.
The study found the difference in treating major depression as measured by improvement in HAM-D scores between St. John's wort and the placebo was not statistically significant. This means that:
A) we cannot make a 95 percent confidence statement.
B) a difference this big could easily occur just by chance even if St. John's wort does no better than the placebo.
C) the placebo makes no difference in the subjects' depression.
D) the study was badly designed.

Question

Quizplus · Accepted Answer

A non-significant result means that we cannot reject the null hypothesis that there is no difference between St. John's wort and placebo in treating major depression. However, it is possible that a difference exists, but the study was not able to detect it with enough certainty. There is a possibility that the observed difference could occur by chance, which is why we cannot say with confidence that St. John's wort is effective in treating major depression.

Does St John's Wort Have a Significant Effect in Treating Major