Скачать или смотреть Basic course of biomedical research-Assignment 5

Ecological studies (generate hypothesis)
• Group as the unit of analysis • No individual-level information on the distribution of exposure and disease.
An ecological study is a type of observational study used in epidemiology, public health, and environmental sciences to analyze data at the population or group level, rather than at the individual level.
Relate rate of disease and exposure; principal advantage of an ecological study? generate hypotheses
An ecological study is a type of observational study used in epidemiology, public health, and environmental sciences to analyze data at the population or group level, rather than at the individual level.
Unit of Analysis: Groups or populations (e.g., countries, cities, schools), not individuals.
Exposure and Outcome: Assessed as group averages or rates (e.g., average air pollution level vs. lung cancer incidence per 100,000 people).
Data Sources: Often based on existing (secondary) data such as census data, health registries, environmental monitoring, etc.
An ecological study may explore whether countries with higher average alcohol consumption have higher rates of liver cirrhosis.
Advantages:
1. Quick and inexpensive: Uses readily available data.
2. Useful for hypothesis generation.
3. Can detect population-level trends or environmental influences.
Cross sectional study (generate hypothesis)
• Observation of a cross-section of a population at a single point in time
• Collect information about disease burden (prevalence studies)
Cross sectional survey: major limitation • Prevalent cases (Old and new cases) • Exposure and outcome examined at the same time. e.g. • Obesity and diabetes
Can be used to identify factors associated with outcome: While they cannot establish causality, cross-sectional studies can identify associations between different variables, including potential factors associated with a specific outcome
A cross-sectional study might be used to measure the prevalence of obesity in a particular city (descriptive) or to examine whether there is a relationship between obesity and smoking habits in that same city (analytical). cross-sectional study, the main goal is often to estimate the prevalence

Which of the following designs can be used to document a patient’s response to an innovative intervention? Case report
Test hypothesis (Study etiology of disease)  Analytical study
Choice of study design
1. Qualitative (Person to person interviews, grp. discussion or Quantitative (Questionnaire)
2. Obs. or expt. (Interventional)
3. Retro (Case control) or prospective (Cohort)
Study designs
1. Observational [Odds ratio (OR) Control the case in the OR], Cohort = relative risk
a. Descriptive :- Case series, Ecological, Cross-sectional, case report
b. Analytical :- Case control (OROdds ratio), Cohort (RR Relative risk/risk ratio)
2. Experimental/Interventional (RCT)
3. Clinical trial (Can I SWIM ?  Safety, does it Work, any Improvement, can it stay in Market
a. 1  safety and acceptability; 50 healthy
b. 2  Long term safety, dose, schedule, early indications of efficacy; low risk 100-500
c. 3  Effectiveness; high risk more than 1000
d. 4  Post-marketing surveillance; community based more than 1000