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Observational studies: what is a cohort study?

2007· article· en· W2080784692 on OpenAlexafffund
Jason Tay, Alan Tinmouth

Bibliographic record

VenueTransfusion · 2007
Typearticle
Languageen
FieldMedicine
TopicBlood groups and transfusion
Canadian institutionsCanadian Blood ServicesOttawa HospitalUniversity of Ottawa
FundersCanadian Institutes of Health ResearchCanadian Blood Services
KeywordsEpidemiologyMedicineClinical epidemiologyFamily medicineEmergency departmentObservational studyLibrary scienceGerontologyPathologyNursing

Abstract

fetched live from OpenAlex

escriptive studies (also known as observational studies) are considered "natural" experiments, where the investigator lets nature take its course.Such studies may provide information on the effect of a treatment, prevention, or other exposures.The objective of an observational study is to determine the relationship between an exposure and an outcome with validity and precision while minimizing the use of resources.There are two common types of observational studies: cohort and case-control studies.Several other study designs are available and include cross-sectional and ecologic studies.Experimental study designs such as the classical randomized controlled trials are often considered the most robust method to test hypotheses (i.e., prove causation).In many instances, however, this may not be feasible and alternative study designs are required.Descriptive studies fill this role by attempting to answer the "W's": why, where, who, what, and when.Although they cannot prove or disprove a hypothesis, they can demonstrate a relationship or association. 1 The conduct and results of such studies may then inform the development of more robust randomized controlled trials.

Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.

How this classification was reachedexpand

Full frame machine prediction

Teacher imitation

Not calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.

metaresearch head score (Codex)0.260
metaresearch head score (Gemma)0.574
Version: metacan-v3-hybrid-931329e0061cValidation status: machine_predicted_unvalidated
Candidate categoriesMetaresearch
Consensus categoriesMetaresearch
DomainCandidate signal: Methods · Consensus signal: none
Study designCandidate signal: Theoretical or conceptual · Consensus signal: none
GenreCandidate signal: Methods · Consensus signal: none
Teacher disagreement score0.740
Threshold uncertainty score0.912

Distilled classifier scores by category (both heads)

CategoryCodexGemma
Metaresearch0.2600.574
Meta-epidemiology (narrow)0.0010.002
Meta-epidemiology (broad)0.0080.004
Bibliometrics0.0110.017
Science and technology studies0.0040.013
Scholarly communication0.0110.021
Open science0.0060.004
Research integrity0.0150.011
Insufficient payload (model declined to judge)0.0060.002

Machine scores (provisional)

The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.

Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.

Opus teacher head0.071
GPT teacher head0.347
Teacher spread0.276 · how far apart the two teachers sit on this one work
Validation statusscore_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it

Classification

machine, unvalidated

Machine predicted; the direct Gemma label and the distilled Codex classifier agree on what is shown here.

Study designTheoretical or conceptual
DomainMethods
GenreMethods

How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".

Quick stats

Citations4
Published2007
Admission routes2
Has abstractyes

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