Which is better – a meta-analysis of all good quality evidence, or the results of the most precise trial contributing to that meta-analysis? Of course there can’t be a definitive answer to that question if there is no gold standard. However, a single large trial does produce the more pessimistic evidence on treatment effect on average, according to Berlin and Golub. Given a premise that bias tends towards ‘optimistic’ results, then the large “definitive” trial is the less biased on average.
— Richard Lilford, CLAHRC WM Director
- Berlin JA, Golub RM. Meta-analysis as Evidence. Building a Better Pyramid. JAMA. 2014; 312(6): 603-5.