In scientific studies, different groups are compared to see if there is a meaningful difference in outcome between them. This means that researchers want to know if one group will do the same, worse, or better than the other group or groups. A difference between groups is meaningful if it is bigger than what you would expect if it were just up to chance. When the difference is meaningful this way, it is called statistically significant.
Read about clinical trials.
Audio contributed by: Lisa Vidal