longitudinal study

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study

 [stud´e]
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.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

lon·gi·tu·di·nal stud·y

a study of the natural course of life or disorder in which a cohort of subjects is serially observed over a period of time and no assumptions need be made about the stability of the system.
Synonym(s): diachronic study
Farlex Partner Medical Dictionary © Farlex 2012

longitudinal study

An epidemiologic study that follows a population forward over time, evaluating the effects of one or more variables on a process. If individuals are followed, it is termed a longitudinal cohort study. If classes—e.g., age classes—are studied, it is a longitudinal cross-sectional study. Longitudinal studies are the converse of horizontal studies.
 
Examples
Cohort studies; case-control studies; Framingham Study in Massachusetts, US; Port Pirie study, an ongoing analysis of the long-term effects of blood lead levels on IQ.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.

longitudinal study

Diachronic study Statistics A study that follows the same persons over time, evaluating the effects of one or more variables on a processtime Examples Cohort studies, case-control studies. Cf Cross-sectional study, Horizontal study.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.

lon·gi·tu·di·nal stud·y

(lonji-tūdi-năl stŭdē)
A study of the natural course of life or disorder in which a cohort of subjects is serially observed over a period of time and no assumptions need be made about the stability of the system.
Medical Dictionary for the Dental Professions © Farlex 2012
References in periodicals archive ?
3) When the design of a research is a longitudinal study with repeated measures, and its data are appropriately analyzed with up-to-date statistical methods, this situation allows dealing with smaller sample size given the efficiency of the longitudinal data analysis methods, which improves when adding more measurements per subject (4).
Figure 3 shows the composition of the longitudinal data by panel and by the number of times establishments appear in the longitudinal data.
Such data with a limited number of repeated measurements are referred to as longitudinal data. [5] In many longitudinal data designs in psychiatric research, subjects receiving different interventions or those exposed to different potential risk factors are repeatedly evaluated at a number of time points separated by specified intervals.
Twisk (epidemiology and biostatistics and health sciences, Vrije U., Amsterdam, the Netherlands) provides a guide for non-statisticians and researchers working with longitudinal data from epidemiological and clinical studies that explains techniques available for data analysis, from simple techniques like the paired t-test and summary statistics, to more complex ones like generalized estimating equations and mixed model analysis.
This question was central to a study completed recently by the National Center for Analysis of Longitudinal Data in Education Research.
The main purpose of JA Kids: The Jamaican Birth Cohort Study 2011 is to collect primary, longitudinal data on the physical and emotional well-being of parents and children aged zero to two years in Jamaica.
The fourth round of longitudinal data collection occurred in 2007 and 2008 at an average age of 29, and included 11,666 people, 49% women; among the sample, 66% were white, 15% African American, 12% Hispanic, and 7% other.
Analysis of longitudinal data, collected at four times during the course of the survey to date showed hyperactive-impulsive symptoms linked with increasing BMI over the course of adolescence and into adulthood.
The Request for Applications for 84.305A has been revised to include a new research topic, Analysis of Longitudinal Data to Support State and Local Education Reform.
The graduate statistics textbook develops mixed effects models with measurement errors or censored responses, frailty models, joint models of survival data and longitudinal data, and robust methods for mixed effects models.
To begin to address this issue, the Robert Wood Johnson Foundation and CDC recently funded three national public health associations to collect longitudinal data through periodic surveys of the nation's local public health agencies, state health agencies, and local boards of health.

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