Reporting novel data

Primary research studies report data or findings collected by the authors. This includes data from a cohort of patients or single patients, or experimental bench science. In the case of human subjects, the primary research outcomes are relevant to that group, but you do not know if the findings can be generalised to others. If the characteristics of the group or person you are caring for are very similar, then it may be relevant to your question.

The type of primary research is defined by the nature of the findings collected:


Quantitative research generates numerical data or data that can be converted into numbers for analysis.


Qualitative research describes attitudes and behaviour without collection of numerical data.

Mixed methods

Mixed methods studies combine qualitative and quantitative research approaches.

Patient experience is an important primary outcome in palliative care research and qualitative research can help you to examine this. [1] However, in developing policy or in allocating resources quantitative evidence is often asked for. Mixed methods research can give you both, but it is also more complex and as with any study type not always appropriate. [1] In palliative care research you will find that most publications are generally based on either a quantitative or qualitative approach. [2]

Quantitative and Qualitative - what's the difference?

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Research type is also defined by how and what is done


Interventional research is where participants receive specific interventions according to a pre-specified protocol. The influence of factors other than the intervention can be minimised through randomisation to receive either the intervention or not (control group).


Observational research is where the course of events is studied or observed without any intervention from the researcher. In this case there is no way to control for different factors that might influence the outcome.

Primary study definitions and examples in palliative care [3]

A comparative observational study in which the investigator selects people who have an outcome of interest (for example, developed a disease) and others who have not (controls), and then collects data to determine previous exposure to possible causes. 

See PubMed Example: Palliative surgery as a bridge to systemic treatment for malignant bowel obstruction due to peritoneal metastases: A retrospective, case-control study.

An observational study in which a group or 'cohort' of people are observed over time in order to see who develops the outcome of interest. 

See PubMed Example: Is there lower utilisation of hospice care services during end-of-life care for people living with HIV? A population-based cohort study

A correlation study is an observational study in which the association (or correlation) between 2 or more variables is investigated. 

See PubMed Example: Relationship between mental health and spiritual wellbeing among hemodialysis patients: a correlation study

An observational study in which the source population is examined to see what proportion has the outcome of interest, or has been exposed to a risk factor of interest, or both. 

See PubMed Example: Impact of end-of-life respiratory modalities on quality of dying and death and symptom relief in patients with interstitial lung disease: a multicenter descriptive cross-sectional study.

A specific type of interview study (see interview study) where multiple groups of people are interviewed by 1 or more facilitators or interviewers. The method explicitly includes and uses the group interaction to generate data.

See PubMed Example: Supportive and palliative care indicators tool (SPICT™) in a Danish healthcare context: translation, cross-cultural adaptation, and content validation.

An approach in which multiple (more than 2) observations are made on the same individuals, or groups of individuals, over time.

See PubMed Example: Supportive and palliative care indicators tool (SPICT™) in a Danish healthcare context: translation, cross-cultural adaptation, and content validation.

A qualitative method of data collection where participant's views are elicited via verbal interviews.

See PubMed Example: Challenges and Strategies Regarding Sedation at the End of Life in Hospitals and Nursing Homes. 

See PubMed Example: Challenges and Strategies Regarding Sedation at the End of Life in Hospitals and Nursing Homes.

These are trials where participants (or clusters) are allocated to receive either intervention or control (or comparison intervention) but the allocation is not randomised. 

See PubMed Example: Next of kin participation in the care of older persons in nursing homes: a pre-post non-randomised educational evaluation, using within-group and individual person-level comparisons.

Prospective cohort studies involve following groups of people forward in time to assess who develops the outcome of interest, often by conducting a series of cross-sectional studies.

See PubMed Example: Palliative care and catastrophic costs in Malawi after a diagnosis of advanced cancer: prospective cohort study. 

RCTs are generally considered to be the most rigorous experimental study design as the randomisation of participants helps to minimise confounding and other sources of bias.

See PubMed Example: a randomized controlled trial on the efficacy of life review therapy targeting incurably ill cancer patients: do their informal caregivers benefit?

In retrospective cohort studies, both the exposure and outcomes of interest all take place in the past relative to the starting point of the study.

See PubMed Example: C-reactive protein and white blood cell count are adverse prognostic makers for patients with advanced cancer on parenteral nutrition in a palliative care unit setting: a retrospective cohort study.

Epidemiological studies - made easy! 

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  1. Farquhar MC, Ewing G, Booth S. Using mixed methods to develop and evaluate complexinterventions in palliative care research. Palliat Med. 2011 Dec;25(8):748-57. doi: 10.1177/0269216311417919. Epub 2011 Aug 1.
  2. Fàbregues S, Hong QN, Escalante-Barrios EL, Guetterman TC, Meneses J, Fetters MD. A Methodological Review of Mixed Methods Research in Palliative and End-of-Life Care (2014-2019). Int J Environ Res Public Health. 2020 May 29;17(11):3853. doi: 10.3390/ijerph17113853
  3. National Institute for Health and Care Excellence. Appendix D Glossary of study designs [Internet]. London, UK: National Institute for Health and Care Excellence; 2012 Sep. [cited 2022 Feb 17].

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