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Qualified Majority

In the context of EU legislation, a qualified majority is achieved when two conditions are met simultaneously: at least 55% of Member States vote in favour, and the proposal is backed by Member States representing at least 65% of the total EU population. Available at: Qualified majority - Consilium (

Qualitative Study

Qualitative studies are based on collecting information that describes people's perspectives and motivations. Unlike quantitative studies, they do not try to quantify anything or use statistics.

A qualitative study might use focus groups, or interviews or observation, or a combination of methods. Sample sizes (the number of people recruited to take part) are more difficult to predict, and are often smaller than in quantitative studies. Qualitative researchers will often analyse their data as they go along, and stop looking for new people to take part when no new insights are being found.

Qualitative researchers do not assume that they know what the important issues are. Often it is not until the research is underway that the real issues are identified. Therefore, qualitative methods are general designed to give participants the freedom to raise issues that are important to them. For example, topic guides will be developed for interviews rather than tightly defined questionnaires.

Qualitative methods are often used in combination with other methods to provide rich and comprehensive data sets.

Quality Control

Quality Control (QC) is part of the system of ensuring high standards during research, trials and production for medicines. Each step of medicines development and production is managed under a Quality Management (QM) system.

The standards required are known as the Quality Assurance (QA) system, whereas QC is the method used to ensure the standards are met at each step.

Quality management for clinical research is known as Good Clinical Practice (GCP).

Quality of Life

Quality of Life (QoL) is a measure in health economics. It expresses the effect of factors such as symptoms, pain, psychological health, and wellbeing on people's lives. Health-related quality of life (HRQoL) measures are used to calculate the likely impact of treatments on the lives of patients.

Quality-adjusted life year

The quality-adjusted life year (QALY) is a measure in health economics. It expresses the additional number of years which a person lives as a result of receiving a treatment, and takes into account the quality of life of those years. It does this by measuring how important various factors are to patients, such as symptoms, pain, and psychological health.

The calculation of QALYs is a common approach used by health technology assessment (HTA) bodies, which advise about the 'usefulness' of treatments and, in some countries, about whether treatments should be funded by (for example) government health departments.

Quantitative Imaging in Cancer: Connecting Cellular Processes with Therapy

Quantitative Imaging in Cancer: Connecting Cellular Processes with Therapy

Quantitative Study

A quantitative study aims to measure and quantify, and uses statistical methods to analyse data. Unlike qualitative studies, they do not collect information about people™s perspectives and motivations.

Quasi-randomised trial

A quasi-randomised trial is one in which participants are allocated to different arms of the trial (to receive the study medicine, or placebo, for example) using a method of allocation that is not truly random.

Allocation might be based on date of birth, medical record number, or the order in which people were recruited (for example, every other person might be allocated to the placebo group).

With quasi-randomisation there is a greater risk that the investigator will be aware of which participant is in which group. There is therefore a risk of selection bias.