Question

When testing a new​ treatment, what is the difference between statistical significance and practical​ significance? can a treatment have statistical​ significance, but not practical​ significance?

Answer 1

1. For a result to be statistically significant means that the probability of the results observed been due to chance is very low or impossible. For a result to be statiscally significant means that the differences observed between the experimental group and the control group of the experiment is not  due to chance or sampling errors.
Practical significance refers to how practical it is to convert a result observed in the laboratory to use in real world scenario. The difference observed between two variables in an experimental set up may be so small that it may not be worth it to produce it on a large scale for human use.
Thus, the difference between statistical and practical significance is that statistical significance indicates the difference between two variables while practical significance determines if the results is worth been reproduce on large scale.
2. YES, a treatment can have statistical significance but have no practical significance. This means that, even though the treatment is effective, due to some reasons it is not worth it or practical to produce it on a large scale.