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Epi Final
Epidemiology Final Vocab
Term | Definition |
---|---|
Bias | Any effect at any stage of investigation or inference which may produce results that are not "true" |
Case-control Study | Epidemiologic study in which persons with a specific disease (the cases) & the persons without the disease (the controls) are selected; the proportions of cases & controls with certain background characteristics and/or exposure to possible risks are then |
Clinical Trial | A medical or epidemiologic experiment in which subjects in a population are randomly allocated into groups to receive or not to receive an experimental preventive or therapeurtic procedure or interverntion. The results are assessed by comparison or rates |
Cohort study | Study in which persons initially free from the disease under study are selected & their background characteristics and their exposure to possible risk factors ascertained; these individuals are then followed through time and the porportions who develop th |
Control Group | In a case-control study, a group of individuals free of the disease under study who are believed to reflect the the characteristics of the population from which the persons with the disease were drawn. |
Descriptive Study | Study of the occurrence of disease or other condition in populations. The relationship of disease to such demographic charactierics as age, sex, race, occupation and social class, to geographic location, and to time period may be studied. |
Double-blind | A characteristic of an epi study such that neither the members of the study population themselves nor the persons observing the outcome in the members of the study populations know which individuals were exposed or not exposed to the agent under study. |
False Negative Rate | The proportion of persons with a disease in whom a screening test for that disease is negative. |
False Positive Rate | The proportion of persons without a disease in whom the screening test for that disease is positive. |
Intervention Study | Study in which the investigator assigns individuals to be exposed or not to be exposed to a given factor. These individuals are then followed through time and the proportion developing or dying from a disease among those exposed to the factor is compared |
Lead Time Bias | A systematic error arising when follow-up of 2 groups does not begin at strictly comparable times. It commonly refers to the misleading results that may be obtained when length of survival is compared in 2 groups. 1 groups was diagnosed earlier. |
Observational Study | Study in which changes or differences in one characteristic are studied in relations to changes or differences in other characteristics without intervention of the investigator |
Odds Ratio | The ratio of affected to unaffected indivuals among those exposed to a given factor divided by the ratio of affected to unaffected individuals among those not exposed to the factor. In rare disease, the relative risk may be approximated by the odds ratio. |
Placebo | An inactive preparation given to control subjects in a clinical or prophylactic trial; it is used so that the person in the trial does not know whether he/she is getting an active preparation. |
Predictive value (negative) | In screening and diagnostic tests, the probability that a person with a negative test does not have the disease. |
Predictive value (positive) | In screening and diagnostic tests, the probability that a person with a positive tests actually has the disease. |
Relative Risk | The incidence rate (risk) of disease in the exposed group divided by the incidence rate (risk) in the unexposed group |
Reliability (reproducibility) | The extent to which a measurement produces the same results when repeatedly applied to the same situation. |
Secular Trends | Changes in incidence rates , mortality rates, and other indicators of disease frequency that occur gradually over relatively long periods of times. |
Sensitivity | The extent to which a test identifies as positive all individual who have a given disease. |
Specificity | The extent to which a test identifies as negative all individuals who are free of a given disease. |
Validity (accuracy) | The closeness with which a measurement approaches the true or actual value. |