Explanations of how to read clinical trials, registry records, statistics, systematic reviews, funding disclosures and study claims so readers can judge the evidence behind health headlines. This page lists all 15 Clinical Research Explained guides on the topic, each with its opening lines so you can pick the one that matches your question.
Clinical Research Explained is an independent publication. These guides are for education and do not replace care from a qualified professional.
Guides in this section
Crossover CBD Trials: Why the Washout Period Matters
ial Team A washout period is the gap between two treatment periods in a crossover trial, during which participants receive no study treatment so the first one can wear off. It matters because, if the first treatment's effect lingers, the results from the second period cannot be cleanly credited to what was given in that period.
Study Status vs. Posted Results on ClinicalTrials.gov: Reading Two Different Record Fields
A trial record that says "Completed" has not necessarily posted results. The recruitment status describes where the study stands. The results-first-posted date marks when summary results information became available on the registry.
Correlation and Causation in Health Headlines: Five Questions Before Sharing a Claim
. This article has not been peer-reviewed or clinically reviewed, and it is general education, not medical advice. A headline says a food, supplement, or habit is "linked to" a longer life, a lower cancer risk, or a slimmer waistline.
Supplement Study Dosage: How to Compare the Research Amount With a Label
This article has not been peer reviewed or clinically reviewed and is not individual medical advice. Checked against the cited sources on September 30, 2026. See the Medical Disclaimer .
Clinical Trial Status Labels: Recruiting, Active, Completed, and Withdrawn
A status label on a trial registry record describes where a study is in its lifecycle. It does not tell you whether a treatment works, whether you would qualify, or whether you should take part. Those questions depend on the study's eligibility criteria, the study team's screening, and advice from your own clinician.
Study Funding and Conflicts of Interest: What to Look for Before You Rely on a Result
This article has not been peer reviewed or clinically reviewed. It is educational and is not individual medical advice. Funding and disclosed relationships may be reported in more than one place. Look for a funding statement, author disclosure statements or forms, a data-access statement, and, where one is cited, a protocol.
Systematic Review Protocols: Why a Plan Written First Matters
Guidance such as the Cochrane Handbook expects a systematic review to define its question and methods in a written protocol before the work of selecting studies begins.
Primary Outcomes and Secondary Outcomes: What a Trial Was Built to Measure
A primary outcome is the prespecified result a trial treats as most important. Secondary outcomes are other planned measurements that add context. Results that were never planned in advance are exploratory, so this page suggests reading them as questions for further study, not as what the trial set out to answer.
Adverse Event Tables in Clinical Trials: What They Report and What They Leave Open
A study's adverse event table can look like a verdict on safety. It isn't one. That table is a record of what happened to a specific group of trial participants, under specific monitoring conditions, over a specific period of time — and reading it well means understanding what those numbers do and…
Preprints, Peer Review, and Published Papers: How the Evidence Status Changes
Short answer: Before you share or act on a health claim, find out which stage the paper is at: preprint, journal-published, corrected, flagged with an expression of concern, or retracted. Each stage means something different about how far the findings have been checked.
Confidence Intervals in Health Research: What the Range Adds to a Result
. This article has not been peer-reviewed or clinically reviewed, and it is general education, not medical advice. Short answer: a confidence interval shows how precisely a study pinned down its estimate. It marks a range of effects that are compatible with that study's result.
Inclusion and Exclusion Criteria: Who a Clinical Study Can and Cannot Describe
. Last updated September 30, 2026. Before trusting a clinical study to answer your own question, check one thing first: did the study actually include people like you? Every clinical study is built around a specific group of people, defined by inclusion criteria (who is allowed to join) and exclusion criteria (who is kept out).
Systematic Reviews and Meta-Analyses: Why Included Studies Matter
A systematic review or meta-analysis is only as trustworthy as the studies it includes. Two reviews can ask the same question and reach different conclusions simply because they included different sets of studies, using different rules for what counted as "good enough" evidence.
Clinical Trial Registration Numbers: How to Match a Study With Its Registry Record
Most published clinical trials carry a registration number — a short code tied to a public trial registry, such as ClinicalTrials.gov.
Randomized Trial Abstracts: How to Find the Primary Outcome and Time Frame
In a well-reported randomized trial abstract, the primary outcome and its time frame usually sit in two predictable places: a short outcomes phrase inside the Methods portion of the abstract, and a restated version of the same measure inside the Results portion, next to the actual numbers.