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.

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

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.

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.

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.

longitudinal study

a chronological study in epidemiology which attempts to establish a relationship between an antecedent cause and a subsequent effect. See also cohort study.
References in periodicals archive ?
These data are from the BLS National Longitudinal Survey of Youth 1979.
Data for the study was taken from the National Longitudinal Survey of Youth 1979 cohort, a nationally representative sample of 12,686 young men and women who were interviewed on an annual basis from 1979 through 1994 and are currently interviewed on a biennial basis.
htm The Educational Longitudinal Study (ELS) is a longitudinal survey that follows educational transitions of 10th grade students from high school and beyond.
Rissman examines data from the BLS National Longitudinal Survey of Youth 1979 and finds evidence supporting the second view.
Using National Longitudinal Survey of Children and Youth survey data, we identify three homework trends that differentiate the homework activities of full-time employed mothers from the work of "at-home" mothers.
Using data from the National Longitudinal Survey of Youth, this study (N = 1,504) showed that about half the EITC eligible tax fliers in 2001 did not file EITC tax returns and that differences between EITC tax fliers and non-EITC tax fliers varied by birth place, Food Stamp program participation, marital status, race, residence, sex, socioeconomic history, and worker classification.
The analysis was conducted in the British Columbia Inter-university Research Data Centre at the Univorsity of British Columbia and was based on 2000/01 National Longitudinal Survey of Children and Youth and 2001 Census profile.
When National Right to Life News asked Priscilla Coleman, associate professor of human development and family studies at Bowling Green State University, to comment on "Depression and unwanted first pregnancy: longitudinal cohort study," she began by pointing out that Schmiege and Russo re-analyzed the same National Longitudinal Survey of Youth data used in a 2002 BMJ paper written by David Reardon and Jesse Cougle.
Also appropriate for secondary analyses are relevant cross-sectional and longitudinal survey data collected by federal, state, and local government agencies.
Children in lone mother families created after separation or divorce enjoy a higher standard of living, on average, than children born to a young single mother," according to the report, When Parents Separate: Further Findings from the National Longitudinal Survey of Children and Youth.
In a national longitudinal survey of 1,762 adolescents aged 12-17 years, teens in the 90th percentile of TV sex viewing were almost twice as likely to become sexually active during the study year as teens in the 10th percentile.
That's according to a Texas State University study that examined National Longitudinal Survey of Adolescent Health data collected from 1994-96.

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