longitudinal study

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Related to Longitudinal design: cohort design

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.
References in periodicals archive ?
Exhibit 5 shows differences in mean ADL scores between 2005 and 2006 and between 2006 and 2007 according to three study designs (repeat cross-sectional and two longitudinal designs).
This study illustrates the developmental epidemiological perspective in [beta]-thalassaemic children and their family using an accelerated longitudinal design. Such design can test the hypothesized etiological or developmental function of a targeted risk factor within a developmental path and may be used in studying the psychological impact of even other chronic illnesses over the life span of an individual for conceptual and holistic understanding.
The longitudinal design presents the researcher with some challenges though.
Longitudinal designs, on the contrary, can be used to reduce the problems associated with cross-sectional studies: they provide a better opportunity to validate theoretically hypothesized causal relationships between, for instance, work characteristics and stress outcomes (Frese & Zapf, 1988; Zapf, Dormann & Frese, 1996).
(A longitudinal design is defined as one where expectations are measured before the service is delivered and perceptions are captured after the service.) For researchers using the disconfirmation approach, it is not clear whether both expectations and perceptions should be measured in a cross-sectional study or whether a longitudinal design is more appropriate.
"Because of the longitudinal design of this study, and the fact that we were able to take into account other factors that would be related to risk for substance use, this study provides evidence of a specific contribution of energy drink consumption to subsequent substance use."
To our knowledge, this study is the first to examine this relationship using a rigorous longitudinal design. Our study is designed to address the following research hypotheses:
The study, which draws strength both from its large sample size and longitudinal design, makes clear that existing clinical guidelines have not recognized the full impact of VMS on women in midlife.
This study was limited in that it involved selected subjects and was of longitudinal design so it did not include a control group.
The current analyses employed an accelerated longitudinal design (Helms, 1992) to examine growth from 3rd to 8th grade, pooling 5 waves of longitudinal test data that were available.
However, we believe that the longitudinal design of our study (Sokol et al.

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