Summary Research Methods (PDF)
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عبدالرحيم شولح
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This document is a summary of research methods, including epidemiology, and thesis writing. It details steps in the research process as well as different study designs and procedures. The document also goes into details of different study types, such as case reports and cohort studies.
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.. اد /عبد الرحيم شولح 1 9/11/2024 Steps of Research process 42 اد /عبدالرحيم شولح 1/10/2025 A thesis is a long research paper....
.. اد /عبد الرحيم شولح 1 9/11/2024 Steps of Research process 42 اد /عبدالرحيم شولح 1/10/2025 A thesis is a long research paper. It starts with a thesis What is a thesis? statement which is the main point of your thesis paper. It can be a question, a statement, or an assessment. You will need to prove the thesis statement in your thesis with the help of the data that you collect and the analysis you come up with. 43 1/10/2025 45 1/10/2025 47 48 1/10/2025 List of abbreviations Summary 7. Appendices 8. Arabic Summary 1/10/2025 52 Aims of Epidemiologic Research 1. Describe the health status of a Descriptive population epidemiology 2. To assess the public health importance of diseases 3. To describe the natural history of disease, 4. Explain the etiology of disease Analytic 5. Predict the disease occurrence epidemiology 6. To evaluate the prevention and control of disease 7. Control the disease distribution Applied epidemiology Descriptive epidemiology Describes the occurrence of disease (cross- sectional) Descriptive and Analytical Analytic epidemiology: Epidemiology Observational (cohort, case control, cross- sectional, ecologic study) – researcher observes association between exposure and disease, estimates and tests it Experimental (RCT, quasi experiment) – researcher assigns intervention (treatment), and estimates and tests its effect on health outcome 1- Descriptive Studies Characterize who, Person: characteristics where, or when in (age, sex, occupation) Purpose relation to what of the individuals affected by the (outcome) outcome( Place: geography Time: when events (residence, work, (diagnosis, hospital) of the reporting; testing) affected individuals occurred Types 1.1Case Reports Detailed presentation of a single case or handful of cases Generally, report a new or unique finding e.g. previous undescribed disease e.g. unexpected link between diseases e.g. unexpected new therapeutic effect e.g. adverse events Case report: It is a report that documents unusual medical occurrences that can represent the first clue in the identification of new disease or adverse effect of exposures (based on one patient). 1.2 Case Series Experience of a group of patients with a similar diagnosis Assesses prevalent disease Cases may be identified from a single or multiple sources Generally, report on new/unique condition May be only realistic design for rare disorders Case series: It is a collection of different case reports, thus based on more than one patient Cross-Sectional Study as a Descriptive Study Purpose: To learn about the characteristics of a population at one point in time (like a photo “snapshot”) Design: No comparison group Population: All members of a small, defined group or a sample from a large group Results: Produces estimates of the prevalence of the population characteristic of interest Cross Sectional Study Design Cross-sectional Design factor present No Disease factor absent Study population factor present Disease factor absent time Study only exists at this point in time 2- Analytical Studies Case-Control Studies Cases: Disease Controls: No disease factor present Cases (disease) factor absent Study population factor present Controls (no disease) factor absent present past time Study begins here Try to conduct the Case – Control Study Exercise Epidemiologic Study Designs Cohort Studies – an “observational” design comparing individuals with a known risk factor or exposure with others without the risk factor or exposure – looking for a difference in the risk (incidence) of a disease over time – best observational design – data usually collected prospectively (some retrospective) disease Factor present no disease Study population free of disease disease Factor absent no disease present future time Study begins here Timeframe of Studies Prospective Study - looks forward, looks to the future, examines future events, follows a condition, concern or disease into the future time Study begins here Prospective Cohort study Exposed Outcome Measure exposure and confounder variables Baseline Non-exposed Outcome time Study begins here Prospective cohort studies Group participants according to past or current exposure and follow up into the future to determine if the outcome occurs Measurement of the Associations in Cohort Study Design Relative Risk (RR): Compare the risk of developing the disease when exposed to the risk factor to that in the absence of the risk factor. It shows how many times the exposed are more likely to develop the disease compared to the non-exposed Diseased Not Diseased Total Exposed A B A+B Unexposed C D C+D The incidence of disease among exposed = No. 𝒐𝒇 𝒅𝒊𝒔𝒆𝒂𝒔𝒆 𝒄𝒂𝒔𝒆𝒔 𝒂𝒎𝒐𝒏𝒈 𝒆𝒙𝒑𝒐𝒔𝒆𝒅 𝒊𝒏𝒅𝒊𝒗𝒊𝒅𝒖𝒂𝒍𝒔 No 𝒐𝒇 𝒇𝒐𝒍𝒍𝒐𝒘𝒆𝒅 𝒖𝒑 𝒆𝒙𝒑𝒐𝒔𝒆𝒅 𝒊𝒏𝒅𝒊𝒗𝒊𝒅𝒖𝒂𝒍𝒔 𝒅𝒖𝒓𝒊𝒏𝒈 𝒂 𝒄𝒆𝒓𝒕𝒂𝒊𝒏 𝒕𝒊𝒎𝒆 𝒑𝒆𝒓𝒊𝒐𝒅 = 𝑨 𝑨+𝑩 The Incidence of disease among non-exposed = No 𝒐𝒇 𝒅𝒊𝒔𝒆𝒂𝒔𝒆 𝒄𝒂𝒔𝒆𝒔 𝒂𝒎𝒐𝒏𝒈 𝒏𝒐𝒏− 𝒆𝒙𝒑𝒐𝒔𝒆𝒅 𝑰𝒏𝒅𝒊𝒗𝒊𝒅𝒖𝒂𝒍𝒔 No 𝒐𝒇 𝒇𝒐𝒍𝒍𝒐𝒘𝒆𝒅 𝒖𝒑 𝒏𝒐𝒏−𝒆𝒙𝒑𝒐𝒔𝒆𝒅 𝒊𝒏𝒅𝒊𝒗𝒊𝒅𝒖𝒂𝒍𝒔 𝒅𝒖𝒓𝒊𝒏𝒈 𝒂 𝒄𝒆𝒓𝒕𝒂𝒊𝒏 𝒕𝒊𝒎𝒆 𝒑𝒆𝒓𝒊𝒐𝒅 = 𝑪 𝑪+𝑫 Relative Risk = 𝑰𝒏𝒄𝒊𝒅𝒆𝒏𝒄𝒆 𝒐𝒇 𝒕𝒉𝒆 𝒅𝒊𝒆𝒂𝒔𝒆 𝒂𝒎𝒐𝒏𝒈 𝒆𝒙𝒑𝒐𝒔𝒆𝒅 𝑰𝒏𝒄𝒊𝒅𝒆𝒄𝒏𝒆 𝒐𝒇 𝒕𝒉𝒆 𝒅𝒊𝒔𝒆𝒂𝒔𝒆 𝒂𝒎𝒐𝒏𝒈 𝒏𝒐𝒏−𝒆𝒙𝒑𝒐𝒔𝒆𝒅 = 𝑨 𝑪 𝑨+𝑩 𝑪+𝑫 Interpretation of Relative Risk (RR): / Experimental Studies investigator can “control” the exposure akin to laboratory experiments except living populations are the subjects generally involves random assignment to groups clinical trials are the most well known experimental design the ultimate step in testing causal hypotheses Experimental Studies In an experiment, we are interested in the consequences of some treatment on some outcome. The subjects in the study who actually receive the treatment of interest are called the treatment group. The subjects in the study who receive no treatment or a different treatment are called the comparison group. Epidemiologic Study Designs Randomized Controlled Trials (RCTs) – a design with subjects randomly assigned to “treatment” and “comparison” groups – provides most convincing evidence of relationship between exposure and effect – not possible to use RCTs to test effects of exposures that are expected to be harmful, for ethical reasons RANDOMIZATION outcome Intervention no outcome Study population outcome Control no outcome baseline future time Study begins here (baseline point) Epidemiologic Study Designs Randomized Controlled Trials (RCTs) – the “gold standard” of research designs – provides most convincing evidence of relationship between exposure and effect trials of hormone replacement therapy in menopausal women found no protection for heart disease, contradicting findings of prior observational studies