This article is the second part of the series ‘The How and the Why: Interpreting Scientific Studies’, brought to you by Research Matters. The series focuses on the method of scientific studies, including emphasising the importance of meta-analyses, the repercussions of the replication crisis and the inclusion of ethics in experimental biology. We hope this series will better enable our readers to understand and evaluate scientific research they are interested in and those that could impact their lives.

Jack: That, my dear Algy, is the whole truth pure and simple.
Algernon: The truth is rarely pure and never simple.
—  Oscar Wilde in The Importance of Being Earnest

In a series of articles, Research Matters tries to explain the commonly accepted process of scientific methodology, the interpretation of scientific studies and the obvious pitfalls. It is hoped that this series will help lay public in analysing any understanding published scientific studies for what they are, instead of believing just because ‘scientists say so’. This article is the first in the series.