Question

Research Method

What is the difference between statistical significance and clinical significance? Search the literature and cite at least one or two examples that illustrate the differences between the two.

Answer 1

Clinical significance is the practical importance of the treatment effect, whether it has a real, palpable, noticeable effect on daily life. For example, imagine a safe treatment that could reduce the number of hours you suffered with flu-like symptoms from 72 hours to 10 hours. Would you buy it? Yes, probably! When we catch a cold, we want to feel better, as quickly as possible. So, in simple terms, if a treatment makes a positive and noticeable improvement to a patient, we can call this ‘clinically significant’ (or clinically important).

In contrast, statistical significance is ruled by the p-value (and confidence intervals). When we find a difference where p < 0.05, we call this ‘statistically significant’. Just like our results from the above hypothetical trial. If a difference is statistically significant, it simply means it was unlikely to have occurred by chance. It doesn’t necessarily tell us about the importance of this difference or how meaningful it is for patients.