Different types of research article and where to find them

Aim of the article – learning about different types of research article and where to find them.

For anyone interested in finding out more about herbs or natural medicines, looking for research articles can be one place to start. When I speak to people about herbs, they are often surprised to find that there is a growing base of evidence supporting their use, and importantly, helping us understand how herbs are acting in the body.

How to find research articles?
The place I’ve used nearly every day for as long as I can recall now is PubMed – a free electronic bibliographic database from the US National Library of Medicine (NLM).

Just as you would do a search engine search, for example “holidays + Spain”, you will have a think about your keywords (holidays, Spain) and also combine them up, not using the ‘+’ sign but the word AND (these are called Boolean terms and mean the same thing).

So if you want to go to PubMed and search “Turmeric AND human” please go ahead. What you’ll see is a list of all the research papers and a little graph that shows you how the numbers of papers looking at the herb is greatly increasing year on year. So that is the growing evidence base I was talking about, and what that also means, is it gets more and more complicated to actually find good articles that are helpful to us.

Screengrab from a simple PubMed.gov search.

What are different types of articles?
We also need to consider what type of articles we are looking for. When researchers write articles, they can be of different types, as shown in the diagram.

Types of research diagram — Different types of research you may come across reading about herbs

Some of these types of research approaches are:

Review – an overview of all the papers in an area.

Original research – they might have done some experiments and found out new things.

Clinical trial – this is the term to describe a human study, but it might be a pilot study at a small scale and not using precise methods.

Randomised controlled trial – or RCT – this is a human study that does use precise methods; patients are ‘randomly’ allocated to groups, and there is a test (which could be turmeric) and it is compared to a control (or placebo).

Systematic review – this is a type of review that is designed to answer a specific question by finding all the RCT in an area, and it follows a number of methodological steps.

Meta-review – sometimes there are so many RCT, and researchers have compiled these up into even large numbers of SRs, then we might do a meta-review or overview of reviews, to draw conclusions from all of them.

What about evidence hierarchies?
People often talk of an evidence hierarchy but I don’t like this so much as it suggests that some forms of research are more important than others. All types of research help put the pieces in the jigsaw to understand our health or the world around us. I’m a big fan of what we call ‘qualitative’ research, which helps generate ideas, and understand our thoughts and attitudes. You might do this research through interviewing people which is a great skill and is always very illuminating.

When I’ve talked about experiments or RCT or SR, we mean ‘quantitative’ research – think of quantifying, and that involves gathering numbers.

New words and abbreviations
Qualitative – qual
Quantitative – quant
Review
Clinical trial
PubMed
Systematic review
Meta-review
Randomised controlled trial – RCT

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