File Name: epidemiological study designs advantages and disadvantages .zip
We previously discussed descriptive epidemiology studies, noting that they are important for alerting us to emerging health problems, keeping track of trends in the population, and generating hypotheses about the causes of disease. Analytic studies provide a basic methodology for testing specific hypotheses. The essence of an analytic study is that groups of subjects are compared in order to estimate the magnitude of association between exposures and outcomes.
Oxford University Press makes no representation, express or implied, that the drug dosages in this book are correct. Readers must therefore always check the product information and clinical procedures with the most up to date published product information and data sheets provided by the manufacturers and the most recent codes of conduct and safety regulations. The authors and the publishers do not accept responsibility or legal liability for any errors in the text or for the misuse or misapplication of material in this work. Except where otherwise stated, drug dosages and recommendations are for the non-pregnant adult who is not breastfeeding. Epidemiologists must have a sound understanding of the principles of study design. Ethical considerations naturally prevent us from allocating potentially harmful exposures on an experimental basis in human populations. Observational studies are inherently more vulnerable to the effect of bias and confounding.
What is epidemiology? What can epidemiology tell us? How are epidemiology studies conducted? What are the different types of epidemiology study designs? What are the limitations of epidemiology studyies? How are the results of epidemiology studies interpreted? Epidemiology is the study of the distribution of diseases in populations and of the factors that affect this distribution, or in other words epidemiology is the study of how often diseases occur in different groups of people and why.
Medwave se preocupa por su privacidad y la seguridad de sus datos personales. Observational studies evaluate variables of interest in a sample or a population, without intervening in them. They can be descriptive if they focus on the description of variables, or analytical when comparison between groups is made to establish associations through statistical inference. Cross-sectional studies collect the data of the exposure variable and the outcome at the same time, to describe characteristics of the sample or to study associations. Ecological studies describe and analyze correlations among different variables, and the unit of analysis is aggregated data from multiple individuals. In both types of studies, associations of interest for biomedical research can be established, but no causal relationships should be inferred. In this review, we address general theoretical concepts about cross-sectional and ecological studies, including applications, measures of association, advantages, disadvantages, and reporting guidelines.
A study that compares patients who have a disease or outcome of interest cases with patients who do not have the disease or outcome controls , and looks back retrospectively to compare how frequently the exposure to a risk factor is present in each group to determine the relationship between the risk factor and the disease. Case control studies are observational because no intervention is attempted and no attempt is made to alter the course of the disease. The goal is to retrospectively determine the exposure to the risk factor of interest from each of the two groups of individuals: cases and controls.
The prodominant study designs can be categorised into observational and interventional studies. Observational studies, such as cross-sectional, case control and cohort studies, do not actively allocate participants to receive a particular exposure, whilt interventional studies do. Each of the above study designs are described here in turn.
Epidemiologists use primary and secondary data sources to calculate rates and conduct studies. Primary data is the original data collected for a specific purpose by or for an investigator. For example, an epidemiologist may collect primary data by interviewing people who became ill after eating at a restaurant in order to identify which specific foods were consumed. Collecting primary data is expensive and time-consuming, and it usually is undertaken only when secondary data is not available.
Cohort studies are the analytical design of observational studies that are epidemiologically used to identify and quantify the relationship between exposure and outcome. Due to the longitudinal design, cohort studies have several advantages over other types of observational studies. The purpose of this chapter is to cover the various characteristics of prospective cohort studies.
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