Types of research 

Many different types of health research are going on at any one time.

Some studies may look at the effects of standard treatments, while other research may investigate whether new treatments offer any benefit, or how the NHS can best organise and provide services.

The main types of health research are explained below.

Clinical research 

Most research in the NHS involves people – often patients – and is usually referred to as "clinical research" or "medical research".

One particular type of research, known as clinical trials, compares the effects – both wanted and unwanted – of two or more treatments.   

Observational research

Observational research uses data collected during routine clinical care to analyse:

  • the health of the population
  • the natural history of disease 
  • the safety and cost effectiveness of healthcare treatments and therapies used in daily clinical practice

Laboratory or test tube research

Before new treatments are tested in clinical trials, they're often tested in laboratories. Only when laboratory research has shown they're likely to work and unlikely to cause serious side effects will these treatments go on to be tested in clinical trials.

Medicines will often be tested on cells taken from living tissue that are grown and kept alive artificially (cell cultures). These cell cultures can't survive on their own, and once the supply of nutrients, warmth and oxygen is removed, they die.

Research using cell cultures is often called test tube or "in vitro" (meaning "in glass") research, even though a lot of laboratory equipment is now made of plastic.

Cell cultures may, for example, be used to assess the effects of possible drug treatments on cancer cells. Chemicals shown to kill cancer cells in the laboratory may be tested in further research as possible cancer drugs.


Epidemiology is a special branch of research that looks at patterns of illness and disease in groups of people. It tries to identify the causes of disease. 

Some epidemiology studies compare people who have a disease (cases) with people without the disease (controls).

Other studies look at a group of people (a cohort) over time to see what happens. Those who develop a condition and those who don't may then be compared.

A third type of epidemiology study looks at patterns in populations, and may find associations between environmental factors, such as diet, and disease.

The main challenge faced by epidemiology is that while studies often identify strong links (associations), this doesn't prove that one thing has caused the other. Further research is usually necessary to help decide whether this is indeed the case.

Epidemiology has nevertheless made some of the most important medical discoveries, including:

  • smoking tobacco is the main cause of lung cancer  
  • the health risks of high-fat diets and lack of physical activity

It may seem obvious now that not smoking and being active is healthy, but this wasn't always the case.

Animal research

Research on animals is a subject of public debate and controversy, and many people have strong feelings about it.

All medicines must, by law, be tested on animals before being given to humans in clinical trials.

There are regulations to ensure animal research is only carried out when there's no alternative, and it's carried out humanely and is likely to bring real benefits in terms of useful knowledge.

The GOV.UK website has more information about research and testing using animals.

Computer models

It's now possible for computers to try to simulate how the human body works, just as a computer game can imitate the way a car works.

As the human body is extremely complicated, computer models are currently unable to give reliable findings about how the body really behaves. However, they are already giving useful first suggestions to researchers.

The smoking and lung cancer link

In the 1940s, there were different theories about why there had been such a rapid rise in lung cancer over the previous 30 years.

An initial study of 700 people admitted to hospital with lung cancer revealed that nearly all were smokers. The proportion was much higher than for patients admitted to hospital for other reasons.

A careful follow-up study of 40,000 doctors over three years strengthened the evidence of a link, and convinced healthcare professionals of the dangers of smoking.

Page last reviewed: 05/01/2015

Next review due: 05/01/2017