cohort study

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a careful examination of a phenomenon; see also design.
cohort study prospective study.
cross-sectional study one employing a single point of data collection for each participant or system being studied. It is used for examining phenomena expected to remain static through the period of interest. It contrasts with a longitudinal s.
electrophysiological s's (EPS) studies from within the heart of its electrical activation and response to electrical stimuli and certain drugs. In general they include intravenous and/or intra-arterial placement of one or more electrode catheters at sites in the atria, ventricles, or coronary sinus, and sometimes the pulmonary artery or aorta. They record activity or stimulate the heart at various rates and cadences and are aids in the evaluation of electrophysiologic properties such as automaticity, conduction, and refractoriness. They also initiate and terminate tachycardias, map the sequence of activation, and aid in evaluation of patients for various forms of therapy and for the response to therapy. During these studies catheter ablation procedures, such as radio frequency ablation and electrical ablation, may be performed.
flow study uroflowmetry.
longitudinal study one in which participants, processes, or systems are studied over time, with data being collected at multiple intervals. The two main types are prospective studies and retrospective studies. It contrasts with a cross-sectional s.
pilot study a smaller version of a proposed research study, conducted to refine the methodology of the later one. It should be as similar to the proposed study as possible, using similar subjects, the same setting, and the same techniques of data collection and analysis.
prospective study an epidemiologic study in which the groups of individuals (cohorts) are selected on the bases of factors that are to be examined for possible effects on some outcome. For example, the effect of exposure to a specific risk factor on the eventual development of a particular disease can be studied. The cohorts are then followed over a period of time to determine the incidence rates of the outcomes being studied as they relate to the original factors in question. Called also cohort study.

The term prospective usually implies a cohort selected in the present and followed into the future, but this method can also be applied to existing longitudinal historical data, such as insurance or medical records. A cohort is identified and classified as to exposure to the risk factor at some date in the past and followed up to the present to determine incidence rates. This is called a historical prospective study, prospective study of past data, or retrospective cohort study.
retrospective study an epidemiologic study in which participating individuals are classified as either having some outcome (cases) or lacking it (controls); the outcome may be a specific disease, and the persons' histories are examined for specific factors that might be associated with that outcome. Cases and controls are often matched with respect to certain demographic or other variables but need not be. As compared to prospective studies, retrospective studies suffer from drawbacks: certain important statistics cannot be measured, and large biases may be introduced both in the selection of controls and in the recall of past exposure to risk factors. The advantage of the retrospective study is its small scale, usually short time for completion, and its applicability to rare diseases, which would require study of very large cohorts in prospective studies. See also prospective s.
urinary flow study uroflowmetry.
voiding pressure study simultaneous measurement of bladder contraction, urinary flow, and sphincter electromyogram.

co·hort stud·y

a study using epidemiologic methods, such as a clinical trial, in which a cohort with a particular attribute (for example, smokers, recipients of a drug) is followed prospectively and compared for some outcome (for example, disease, cure) with another cohort that does not possess that attribute.
Synonym(s): follow-up study (1)

cohort study

(in research) a study concerning a specific subpopulation, such as the children born between December and May in 1975 or those born in the same months in 1955. See also prospective study.

cohort study

An observational study in which a defined group of people (a cohort) is followed over time and outcomes are compared in subsets of the cohort who were exposed, not exposed, or exposed at different levels to an intervention or other factor of interest. Cohorts can be assembled in the present and followed into the future (a “concurrent cohort study”), or identified from past records and followed from that time up to the present (a “historical cohort study”). Because random allocation is not used, matching or statistical adjustment must be used to ensure that the comparison groups are as similar as possible.
References in periodicals archive ?
For example, because we've learned that users downloading travel apps also download utility apps they'll need on their trip, such as navigators, maps, and trip planners, we're able to use our predictive algorithms to offer more relevant app recommendations based on Actionable Cohort Analysis.
Estimated biomass from the updated cohort analysis (which includes ages >17) indicates that survey estimates may have underestimated the yellowfin sole biomass during the period of increasing stock size in the late 1970's and early 1980's (Fig.
As an example of the interpretation of the cohort analysis in Table 3, consider indigenous males aged 25 to 29 in 1986.
This study employs the age standardization, decomposition, and cohort analysis to examine the life insurance purchase pattern in the U.
For the cohort analysis, six cohorts that could be followed for at least two years were identified.
By utilizing YouAppi's Actionable Cohort Analysis technology, we're able to use our algorithms to uncover the most relevant categories and sub-categories to target with video-based user acquisition campaigns to deliver users with the greatest Lifetime Customer Value.
ITMI is pleased to be working with QIAGEN to provide the clinical research community access to this new solution which can help them jump start a cohort analysis with immediate access to richly annotated data or serve as a control library to improve case solve rates and reduce false positives.
Unlike most of the earlier pediatric series, we also performed a matched cohort analysis with patients who underwent traditional laparoscopy for pyeloplasty and varicocelectomy, and found no significant difference between the 2 techniques.
This work, building on the life cycle bias hypothesis, undertakes cohort analysis and performs regression analysis for all sons (more than 21 years of age), sons of age 25-39 and 30-50 years of age.
The cohort analysis, for example, does not account for some productive post-secondary endeavors, such as military service and apprenticeship programs.
Table 2 shows the actual employment in 2007 along with the 2004-2007 growth rate derived from the cohort analysis of the same age group in 2004 (see table 1), as well as the modeled estimate of 2010 employment for each cohort.
When panel data are not available, a time series of cross-sectional data allows the tracking of cohorts in a sample, a technique which has been referred to in the literature as synthetic cohort analysis or pseudo-panel data modeling (Baltagi 2001; Deaton 1985; Verbeek 1995; Wooldridge 2003).