Reading path

How to read a clinical study

A step-by-step path through the ideas you need to judge almost any treatment study: where it sits in the evidence, how it guards against bias, and how to read what it found.

The path, step by step

1. 1 The Hierarchy of Evidence Explained: From Case Reports to Systematic Reviews

   6 min read

   Where a given study sits, and why design matters before results.

2. 2 What a Control Group Really Does, and Why It Decides What a Study Can Claim

   5 min read

   Why a comparison group is what turns a story into evidence.

3. 3 The First Randomized Controlled Trial and Why Its Design Still Matters

   5 min read

   Why randomizing who gets what removes the biggest hidden biases.

4. 4 Intention to Treat: Why Trials Count Everyone They Enrolled

   4 min read

   How honest trials count everyone they randomized, dropouts included.

5. 5 Confounding and Causation: Why a Real Association Can Still Lie to You

   6 min read

   The main reason an association is not yet a cause.

6. 6 What a Confidence Interval Is Not, and How to Read It as a Measure of Precision

   6 min read

   Reading the uncertainty around a result, not just the headline number.

7. 7 Absolute Versus Relative Risk, and the One Question That Cuts Through the Hype

   7 min read

   Turning a percentage into how many people it actually touches.

8. 8 Number Needed to Treat: How Many People to Help One

   6 min read

   How many people share the effort for each one who benefits.

9. 9 How to Tell Whether a Systematic Review and Meta-Analysis Is Trustworthy

   5 min read

   How many studies are pooled, and when pooling can be trusted.

Each step is a full article on the Reading the Evidence blog.

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