(1) A study in which a group or cohort of individuals is followed for a certain length of time or until a specific outcome is reached. Studies of this type incorporate the strengths of both cohort and case-control studies but eliminates a portion of the methodologic challenges inherent in both types of studies; (2) For each identified case one or more controls are selected, which are still under observation in a cohort study at the time when the case developed the disease of interest [NCI (GitHub - NCI-Thesaurus/thesaurus-obo-edition: OBO Library edition of NCIt)].

Characteristics of case immediately prior to disease onset (sometimes called the hazard period) compared to characteristics of same case at a prior time (that is, control period) [CT.gov (https://prsinfo.clinicaltrials.gov/definitions.html, https://www.clinicaltrials.gov/ct2/about-studies/glossary)].

Studies conducted among family members, such as genetic studies within families or twin studies and studies of family environment [CT.gov (https://prsinfo.clinicaltrials.gov/definitions.html, https://www.clinicaltrials.gov/ct2/about-studies/glossary)].

(1) Group of individuals, initially defined and composed, with common characteristics (for example, condition, birth year), who are examined or traced over a given time period; (2) Data collected over time from the same cohort of respondents. The individuals in the cohort are connected in some way or have shared some significant experience within a given period. In some cases, the samples may differ between waves but are drawn from the same cohort. Examples: birth year, disease (clinical trials), common problem (intervention studies), education, employment, family formation, participation in an event; (3) A form of longitudinal study for the analysis of risk factors following a group of people who do not have a disease, and uses correlations to determine the absolute risk of subject contraction [CT.gov (https://prsinfo.clinicaltrials.gov/definitions.html, https://www.clinicaltrials.gov/ct2/about-studies/glossary), MIABIS (https://github.com/BBMRI-ERIC/miabis), DDI (https://ddialliance.org/Specification/DDI-CV/TimeMethod_1.2.html)].

A cohort study for which the subjects are followed from the time of birth usually including information about gestation and follow up [MIABIS (https://github.com/BBMRI-ERIC/miabis)].

Data are collected over time from, or about, the same sample of respondents. Differs from cohort data in that the selection of respondents is not based on their being connected in some way or having shared some significant experience [DDI (https://ddialliance.org/Specification/DDI-CV/TimeMethod_1.2.html)].

(1) Data collected by observing subjects within the study period, without regard to changes over time. May include more than one collection event. Analysis of cross-sectional data often consists in comparing the differences and similarities among subjects; (2) A type of observational study that involves data collection from a population, or a representative subset, at one specific point in time [MIABIS (https://github.com/BBMRI-ERIC/miabis), DDI (https://ddialliance.org/Specification/DDI-CV/TimeMethod_1.2.html)].

Data are collected repeatedly over time to study change in observations. These are typically "objective" measurements of phenomena that can be observed externally, as opposed to attitudes/opinions or feelings. Examples may include economic/financial indicators, natural/meteorological phenomena, vital statistics, etc. [DDI (https://ddialliance.org/Specification/DDI-CV/TimeMethod_1.2.html)].

An observational study which includes an organized system that uses observational methods to collect uniform data (clinical and other) prospectively for a population defined by a particular disorder/disease, condition (including susceptibility to a disorder), or exposure (including products, health care services, and/or procedures) and that serves a predetermined scientific, clinical, or policy purpose [NCI (GitHub - NCI-Thesaurus/thesaurus-obo-edition: OBO Library edition of NCIt), NFDI4Health]

The study type is unknown [NFDI4Health].