Testing the effects of treatments what is the difference between Clinical significance and statistical signif.?

Question

When testing the effects of treatments what are the differences between Clinical significance versus statistical significance?

Answer 1

Think of it this way. You are running a trial of whether the blue pill or the red pill stops you dying of cancer. You have 100 subjects, 50 of whom get the red pill and 50 get the blue. Of the blue pill subjects, 40 survive 1 year, of the red pill subjects only 1. This is both statistically and clinically highly significant.

In a second trial, you have green and black pills for the same cancer. Of the 50 taking the black pill, 49 die the same day. Of the 50 taking the green pill, 49 die the next day. There is a significant statistical difference in survival, but the difference means nothing clinically.

Answer 2

Clinical significance would related to the individual patient.



Statistical significance would be related to the patient population.



[In medical statistics I believe the 'treatment effect' is measured as a 'mean' - that which occurred most often.]



Example :



The new medicine made a huge difference to 3 patients positive outcomes; so it had "clinical significance" for those 3 patients. However there were 40 patients tested and 30 of them showed no improvement; so the "statistical significance" of the new medicine was negligible for positive outcome.

Answer 3

Statistical significance indicates the difference between two hypotheses are significantly different with certain probability whereas in practical/clinical significance, no probability is involved. The outcome of an experiment is observed as is. As the random sample size becomes larger and larger, the power (probability of making a correct decision) of the statistical test increases. That is, we are more and more correct in declaring significance or non-significance.

Answer 4

The number of people aspirin will help during a heart attack isnt statistically significant.



But being that aspirin wont hurt you, and can help some, it has a TON of clinical significance.