> For the complete documentation index, see [llms.txt](https://knowledge.theholisticcare.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://knowledge.theholisticcare.com/knowledge/research-and-evidence/understanding-study-types.md).

# Understanding Study Types

A plain-language guide to randomized trials, observational studies, systematic reviews, meta-analyses, and laboratory research.

Not all research designs answer the same question.

## Randomized Controlled Trial (RCT)

Participants are assigned to different conditions, ideally by random allocation.

RCTs can provide stronger evidence about whether an intervention caused a difference, but their quality still depends on sample size, comparison group, blinding where possible, attrition, measurement, and analysis.

## Observational Study

Researchers observe naturally occurring differences without assigning the exposure or intervention.

These studies can identify associations, but they are more vulnerable to confounding.

## Systematic Review

Researchers use predefined methods to locate, assess, and synthesise multiple studies on a question.

## Meta-Analysis

A statistical synthesis that combines results across studies.

A meta-analysis can be powerful, but it inherits the strengths and weaknesses of the underlying studies.

## Laboratory or Physiological Study

These studies examine specific mechanisms, brain activity, autonomic responses, or behaviour under controlled conditions.

They can be useful for mechanism, but a short laboratory effect does not automatically translate into long-term real-world benefit.

## Animal Study

Animal research can generate hypotheses about biological mechanisms.

It should not be written as if the same outcome has already been demonstrated in humans.

Good evidence communication starts by naming the design correctly.

## Related guidance

* [Research & Evidence](https://knowledge.theholisticcare.com/knowledge/research-and-evidence)
* [Using the THC Research Hub](https://knowledge.theholisticcare.com/knowledge/research-and-evidence/using-the-thc-research-hub)
* [Reading Limitations & Generalisability](https://knowledge.theholisticcare.com/knowledge/research-and-evidence/reading-limitations-and-generalisability)


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://knowledge.theholisticcare.com/knowledge/research-and-evidence/understanding-study-types.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.