Data for a quantitative study can be collected in a variety of ways, with your choice of method or methods depending on your research question, your study design and the resources you have available.
This page outlines some of the most common data collection methods used in quantitative research, including what they involve and when they are typically used.
Questionnaires are one of the most common ways to collect data in quantitative research, as they allow researchers to obtain information from a large number of people in a structured and efficient way. They typically consist of closed-ended questions with fixed response options (such as multiple choice or rating scales), and may occasionally include short open-ended questions (for example, when suitable response options are not known in advance).
Questionnaires can be delivered online or in person and are often used to collect data on behaviours, attitudes, knowledge, or self-reported health. They are commonly used in cross-sectional, cohort, longitudinal, case control, randomised controlled trial, and quasi-experimental study designs.
If you are interested in learning more about questionnaires, you might find this Scribbr questionnaire design guide helpful. In addition, if you would like to learn how to create and distribute an online questionnaire using Qualtrics, see the Library’s Introduction to Qualtrics module.
Sometimes quantitative research makes use of existing records instead of, or in addition to, collecting new data from participants. These records include information that has already been obtained for other purposes, such as administrative data, electronic medical records, education or employment records, and publicly available datasets.
Using existing records can be cost-effective and time-efficient, especially when large amounts of data are needed or when collecting new data is not feasible. However, because these records were not collected specifically for your research, it is important to consider their relevance, completeness, and accuracy. Existing records are commonly used in cross-sectional, cohort, case control, randomised controlled trial, and quasi-experimental study designs.
Clinical or physiological assessments involve the direct measurement of physical characteristics (such as height or weight) or biological characteristics (such as blood pressure or heart rate) of participants. These assessments are usually carried out by trained staff using standardised procedures and equipment.
This type of data is useful when objective, measurable indicators of health or physical function are needed, rather than relying on self-reported information. Clinical or physiological assessments are commonly used in longitudinal, randomised controlled trial, and quasi-experimental study designs.
Biological samples involve collecting physical specimens from participants, such as blood, saliva, urine, or tissue. These samples can provide objective information about biological processes, genetics, biomarkers, or exposure to environmental factors. Biological samples are particularly useful when studying physiological changes, disease markers, or biochemical responses.
This method is commonly used in cohort and other longitudinal study designs, but can also be incorporated into other designs depending on the research question.
This method involves observational techniques such as watching or recording participants’ behaviours or activities. It can be useful when studying behaviours that are difficult to measure through self-report, for example, how people interact with their environment or how they move through public spaces.
Observations can be recorded by researchers directly (using structured checklists or rating tools) or captured through devices including activity monitors, video recordings, or motion sensors. These methods are most often used in longitudinal study designs, where repeated observation over time can help track patterns or changes in behaviour.
If you would like to consolidate your understanding of the data collection methods outlined above, you may find the following activity helpful: