Research methods
In vitro, in vivo and clinical evidence: different levels of evidence
What each study type answers and why conclusions do not transfer automatically between levels.
In vitro systems allow controlled examination of binding, signalling or cellular response. They are powerful for defined mechanisms, but simplify biology…
02In vivo: an integrated systemAnimal models add absorption, distribution, metabolism and organ interactions. They also introduce species differences and greater variability. ARRIVE 2.0 emphasises transparent…
03Clinical evidence: a defined protocolA clinical trial answers a prespecified question in a defined population, duration and comparator. Even then, generalisation beyond eligibility criteria needs…
In vitro: testing mechanism
In vitro systems allow controlled examination of binding, signalling or cellular response. They are powerful for defined mechanisms, but simplify biology and depend on the selected cell, concentration and endpoint.
In vivo: an integrated system
Animal models add absorption, distribution, metabolism and organ interactions. They also introduce species differences and greater variability. ARRIVE 2.0 emphasises transparent reporting of design, sample size, randomisation and exclusions.
Clinical evidence: a defined protocol
A clinical trial answers a prespecified question in a defined population, duration and comparator. Even then, generalisation beyond eligibility criteria needs care. For a research-material supplier, clinical evidence provides scientific context, not use instructions.
LABORATORY APPLICATION
Turning the principle into an auditable record
State the evidence level in the first sentence of every summary and keep the conclusion within it. Any movement across levels should be explicitly justified and supported by additional sources. A model–measurement–conclusion–limit diagram makes clear where direct data end and hypothesis begins.
PRIMARY & OFFICIAL SOURCES
Sources and further reading
COMMON QUESTIONS
Questions specific to this topic
Are clinical data always superior?
They answer human questions, but may not explain a specific molecular mechanism as clearly as a suitable laboratory model.
What does an animal model add?
Integrated physiology, distribution and organ interactions, together with cross-species translation limits.
Can evidence levels be combined?
Yes, as complementary streams with clear boundaries, not as if they measure the same event.