Some examples of topics examined through epidemiology include as high blood pressure, mental illness and obesity. What are examples of epidemiological studies? The four types of epidemiologic studies commonly used in radiation research are cluster, ecologic, case-control, and cohort studies.
Full Answer
What are the types of epidemiological studies?
Epidemiology examples include classical, clinical, population, sample, and data-focused types. Classical Epidemiology In classical epidemiology, researchers investigate the factors behind what causes diseases among key populations and how they are distributed.
What are the 7 uses of Epidemiology?
Apr 07, 2022 · 1. Observational Studies Observational studies are one of the most common types of epidemiological studies. They comprise of simple questioning, medical examinations and routine laboratory tests or X-rays. Below are its four …
What are the different types of epidemiological study designs?
Sample Size. As discussed above, adequate sample size is critical in conducting a well-designed epidemiologic study. A previous Institute of Medicine (IOM) report discussed the importance of adequate sample size for studying the health of Gulf War veterans: “sufficient samples sizes for each cohort in the study are crucial to ensure adequate statistical power to find differences as …
What is epidemiology and why is it important?
Epidemiologic Study Designs •Descriptive studies –Seeks to measure the frequency of disease and/or collect descriptive data on risk factors •Analytic studies –Tests a causal hypothesis about the etiology of disease •Experimental studies –Compares, for example, treatments
What are examples of epidemiological studies?
The four types of epidemiologic studies commonly used in radiation research are cluster, ecologic, case-control, and cohort studies. An additional approach for estimating risk in radiation research—although strictly not an epidemiologic study—is risk-projection models.
What are the 3 types of epidemiological studies?
Three major types of epidemiologic studies are cohort, case-control, and cross-sectional studies (study designs are discussed in more detail in IOM, 2000). A cohort, or longitudinal, study follows a defined group over time.
What is an example of epidemiological data?
Examples of sources of secondary data that are commonly used in epidemiological studies include birth and death certificates, population census records, patient medical records, disease registries, insurance claim forms and billing records, public health department case reports, and surveys of individuals and ...
What is an epidemiological study?
Epidemiologic studies are the foundation for disease control and prevention through tracking the prevalence of the disease, characterizing the natural history, and identifying determinants or causes of the disease. . It defines risk factors for a disease and targets for preventive medicine.
What is an example of an ecological study?
Examples of the use of ecological studies include: Correlating population disease rates with factors of interest, such as healthcare use. Demonstrating changes in mortality over time (time series) Comparing the prevalence of a disease between different regions at a single point in time (geographical studies)
How do nurses use epidemiology?
Nurse epidemiologists identify people or populations at high risk; monitor the progress of diseases; specify areas of health care need; determine priorities, size, and scope of programs; and evaluate their impact. They generally do not provide direct patient care, but serve as a resource and plan educational programs.
How do you conduct an epidemiological study?
4:519:43Epidemiological Studies - made easy! - YouTubeYouTubeStart of suggested clipEnd of suggested clipWe can then compare the occurrence of an outcome like disease in those who are exposed to aMoreWe can then compare the occurrence of an outcome like disease in those who are exposed to a particular risk factor to those who are not exposed to that risk factor.
What is an epidemiological pattern?
Epidemiological patterns are models of morbidity-mortality or ways of measuring sickness and death that are more prevalent in a given society at specific historical moments.Jun 4, 2019
What are the two main types of epidemiological studies?
There are two main types of epidemiological studies: experimental studies and observational studies and both of them are divided into several subtypes. 1. Observational Studies. Observational studies are one of the most common types of epidemiological studies. They comprise of simple questioning, medical examinations and routine laboratory tests ...
What is epidemiology study?
Types of Epidemiological Studies. The study of disease distributions in the populations and the factors that influence this distribution is called as Epidemiology. In simple words, it is the study of the frequency with which diseases affect different groups of people and the reasons why they occur. Epidemiology has been quite helpful in determining ...
What is an experimental study?
Experimental studies are also main types of epidemiological studies that scientists will carry out experiments where they change things in some sets and compare the outcomes. Under in Vitro studies, a piece of human or animal cell is usually removed from the body for the experiment.
What is the downside of in vitro studies?
The downside of these studies is that their findings are only applicable at a cellular level. Clinical Trials. Clinical trials are experimental studies in which a group of patients is chosen as the subjects.
Why are field trials so expensive?
Since field trials are done in the field, they are more expensive than clinical trials and require a large number of subjects too. Due to the high cost, field trials are only conducted for assessing preventives for extremely dangerous or extremely common diseases.
Why are case control studies important?
Case control studies are analytical studies which compare people that have been diagnosed with a disease with people that haven't been diagnosed with it.
What is clinical trial?
Clinical trials are experimental studies in which a group of patients is chosen as the subjects. The goal of a clinical trial is to assess a new form of treatment or cure for a disease or to discover a preventive measure for diseases like disability or death. Clinical trials are done by choosing a set of patients having a same level ...
What is the importance of identifying and ascertaining a relevant study population and a control or reference population?
It is essential that the study population be representative of the population of interest and that it be large enough to ensure adequate statistical power.
What is the method of assessing exposure to chemicals?
Biomonitoring. Biomonitoring is a method of assessing exposure to chemicals by measuring them or their metabolites in urine and blood.
What is the atemporal relationship?
Atemporal relationship, evidence that exposure occurred before the outcome, is necessary to determine causality. Specificityis defined as the unique association between exposure to a specific agent and a specific health outcome; that is, the health outcome does not arise in the absence of exposure to the agent.
What is biomarker in biology?
Biomarkers are alterations at the cellular, biochemical, or molecular level that can serve as an indicator of exposure to a chemical. They can indicate the absorbed dose or be used to provide an estimate of target-tissue dose. It is critical to understand the timeframe of exposure as reflected by biomarkers.
Is specificity of association rare?
Specificity of association is somewhat rare given the multifactorial etiology of many health outcomes and the broad spectrum of health outcomes that may occur after exposure. Biologic plausibilityreflects knowledge of the biologic mechanism by which an agent can lead to a health outcome.
What is epidemiology research?
In epidemiology, researchers are interested in measuring or assessing the relationship of exposure with a disease or an outcome. As a first step, they define the hypothesis based on the research question and then decide which study design will be best suitable to answer that question. How the investigation is conducted by ...
When is an ecological study used?
Ecological studies are used when data at an individual level is unavailable or when large-scale comparisons are needed to study the population-level effect of exposures on a disease condition. Therefore, ecological study results are applicable only at the population level. The types of measures in ecological studies are aggregates ...
What is a randomized control trial?
Randomized clinical trials or randomized control trials (RCT) are considered the gold standard of study design . In an RCT the researcher randomly assigns the subjects to a control group and an experimental group. Randomization in RCT avoids confounding and minimizes selection bias. This enables the researcher to have similar experimental and control groups thereby enabling them to isolate the effect of an intervention. The experimental group gets the exposure/treatment which can be an agent involved in causation, prevention or treatment of a disease. The control group receives no treatment, a placebo treatment or another standard of care treatment depending on the objective of the study. The groups are then followed prospectively to see who develops the outcome of interest. RCT’s are expensive, and researchers using this study design often face issues with the integrity of randomization due to refusals, drops outs, crossovers, and non-compliance.
What is cross sectional study?
Cross-sectional studies are observational in nature and give a snapshot of the characteristics of study subjects in a single point of time. Unlike cohort studies, cross-sectional studies do not have a follow-up period and therefore are relatively simple to conduct. As the exposure status and outcome of interest information is collected in ...
What is ecological fallacy?
The types of measures in ecological studies are aggregates of individual-level data. These studies, therefore, are subject to a type of confounding called ecological fallacy which occurs when relationships identified at group level data are assumed to be true for individuals.
What is relative risk in a cohort study?
Relative risk is the measure of effect for a cohort study. Cohort studies are subject to very low recall bias, and multiple outcomes can be studied simultaneously. One of the disadvantages of cohort studies is that they are more prone to selection bias.
What is a cohort study?
Cohort Studies. Cohort studies initially classify patients into two groups based on their exposure status. Cohorts are followed over time to see who develops the disease in the exposed and non-exposed groups. Cohort studies can be retrospective or prospective.
What are the types of studies that are conducted in which the unit of obser- vation is a group
It is possible to conduct research in which the unit of obser- vation is a group of people rather than an individual; such studies are called ecologic or aggregate studies . The groups may be classes in a school, factories, cities, counties, or nations. The only requirement is that information on the populations studied is available to measure the exposure and disease distributions in each group. Incidence and mortality are commonly used to quantify disease occurrence in groups. Exposure is also measured
How do field trials differ from clinical trials?
Field trials differ from clinical trials in that they deal with subjects who have not yet got- ten disease and therefore are not patients. Whereas the patients in a clinical trial may face the complications of their disease with high probability during a relatively short time, typi- cally the risk of contracting a given disease for the first time is comparatively small. Conse- quently, field trials usually require a greater number of subjects than clinical trials and there- fore are usually much more expensive. Furthermore, since the subjects are not patients, who usually come to a central location for treatment, a field trial often necessitates visiting sub- jects in the field (at work, home, or school) or establishing centers from which the study can be conducted and to whch subjects are urged to report. These design features add to cost. The expense of field trials limits their use to the study of preventives of either ex- tremely common or extremely serious diseases. Several field trials were conducted to de- termine the efficacy of large doses of vitamin C in preventing the common cold (Kar- lowsh et al., 1975; Dykes and Meier, 1975). Poliomyelitis, a rare but serious illness, was a sufficient public health concern to warrant what may have been the largest formal hu- man experiment ever attempted, the Salk vaccine trial, in which the vaccine or a placebo was administered to hundreds of thousands of school children (Francis et al., 1955). When the disease outcome occurs rarely, it is more efficient to study subjects thought to be at higher risk. Thus, the trial of hepatitis B vaccine was camed out in a population of New York City male homosexuals, among whom hepatitis B infection occurs with much greater frequency than is usual among New Yorkers (Szmuness, 1980).
What is proportional mortality?
proportional mortality study includes only dead subjects. The proportion of dead ex- posed subjects assigned to one or more specific index causes of death is compared with the proportion of dead unexposed subjects assigned to the index causes. The resulting proportional mortality ratio (often abbreviated PMR) is the traditional measure of the ef- fect of the exposure on the index causes of death. Superficially, the comparison of pro- portions of subjects dying from a specific cause for an exposed and an unexposed group resembles a cohort study measuring incidence. The resemblance is deceiving, however, because a proportional mortality study does not involve the identification and follow-up of cohorts. All subjects are dead at the time of entry into the study.
What is a cross sectional study?
study that includes as subjects all persons in the population at the time of ascertain- ment or a representative sample of all such persons, including those who have the dis- ease, and that has an objective limited to describing the population at that time, is usually referred to as a cross-sectional study. A cross-sectional study conducted to estimate prevalence is called aprevalence study. Usually, the exposure information is ascertained simultaneously with the disease information, so that different exposure subpopulations may be compared with respect to their disease prevalence.
What is a cohort study?
In the classic cohort study, the investigator defines two or more groups of people that are fiee of disease and that differ according to the extent of their exposure to a potential cause of the disease. These groups are referred to as the study cohorts (from the Latin word for one of the ten divisions of a Roman legion). In such studies, there is at least one cohort thought of as the exposed cohort-those individuals who have experienced the pu- tative causal event or condition-and another cohort thought of as the unexposed, or ref- erence cohort. There may be more than just two cohorts, but each cohort would represent a group with a different level or type of exposure. For example, an occupational cohort study of chemical workers might comprise cohorts of workers in a plant who work in dif- ferent departments of the plant, with each cohort being exposed to a different set of chemicals. The investigator measures and compares the incidence rate of the disease in each of the study cohorts.
How to define a case control study?
Case-control studies are best understood by defining a source population, which rep- resents a hypothetical study population in which a cohort study might have been con- ducted. If a cohort study were undertaken, the primary tasks would be to identify the ex- posed and unexposed denominator experience, measured in person-time units of experience or as the number of people in each study cohort, and then to identify the num- ber of cases occurring in each person-time category or study cobort. In a case-control study, the cases are identified and their exposure status is determined just as in a cohort study, but denominatofs from which rates could be calculated are not measured. Instead, a control group of study subjects is sampled from the entire source population that gives rise to the cases.
What is community intervention?
The community intervention trial is an extension of the field trial that involves interven- tion on a community-wide basis. Conceptually, the distinction hinges on whether or not the intervention is implemented separately for each individual. Whereas a vaccine is ordinarily administered singly to individual people, water fluoridation to prevent dental caries is ordi- narily administered to indvidual water supplies. Consequently, water fluoridation was eval- uated by community intervention trials in which entire communities were selected and ex- posure (water treatment) was assigned on a community basis. Other examples of preventives that might be implemented on a community-wide basis include fast-response emergency resuscitation programs and educational programs conducted using mass media, such as Project Burn Prevention in Massachusetts (MacKay and Rothman, 1982). Some interventions are implemented most conveniently with groups of subjects smaller than entire communities. Dietary intervention may be made most conveniently by family or household; environmental interventions may affect an entire office, plant, or residential building. Protective sports equipment may have to be assigned to an entire team or league. Intervention groups may be army units, classrooms, vehicle occupants, or any other group whose members are simultaneously exposed to the intervention. The scientific foundation of experiments using such interventions is identical to that of com- munity intervention trials. What sets all these studies apart from ordiaary field trials is that the intervention is more easily assigned to groups than to individuals.
What is the power of a null hypothesis?
Power is the probability that the null hypothesis is rejected, if a specific alternative hypothesis is true. β represents Type II error, the probability of not rejecting the null hypothesis when the given alternative is true.
How does decreasing variability affect power?
Power is inversely related to variability. Decreasing variability will increase the power of a study. If the power of a study is relatively high and a statistically significant effect is not observed, this implies the effect, if any, is small.
How is power related to effect size?
Power is directly related to effect size, sample size and significance level. An increase in either the effect size, the sample size or the significance level will produce increased statistical power, all other factors being equal. Power is inversely related to variability. Decreasing variability will increase the power of a study.
Is money a limited resource?
The FDA, NIH, NCI and most other funding agencies are concerned about sample size and power in the studies they support and do not consider funding studies that would waste limited resources. Money is not the only limited resource.
