epidemiological methods , types of epidemiological study i.e observational and experimental types of observational studies i.e descriptive and analytical studies descriptive describes in term of people , time and place . and Analytical study :it explore about why disease occur , why infected people get the disease and non infected people didn't get it . it tests an hypothesis experimental study cohort study , case control study, cross-sectional study with some examples contained

1. Introduction to epidemiological studies
Kuya Kabalo (BScN,RN,MPH*)

2. Introduction
• Epidemiological studies are designated to determine the extent and
distribution of diseases and their determinants (causes) in human
population with the aim of identifying effective management and
preventive measures

3. Types of research methods
• Observational
• Experimental

4. Types cont.….
• Observational method ;deals with collection of
information without induction and modification to the
study population

5. Types of observational study
• Descriptive are studies which describes disease situation in a particular
area e.g. distribution of diseases in a particular area in relation to age , sex ,
time and place
• Useful in studying the natural history of disease
• Registration of a particular disease is an example of descriptive studies
• Recording characteristics of affected individual by age
,sex,occupational,durationa of symptoms. Of which they are not time
limited

6. Analytical study
• It tries to explain the situation
• Designed to explain the determinative process of the disease
• It answers questions like :why the disease occur in the person
having it not to the non diseased one, why do person fail to
make use of health services, can the decreased incidence of
disease be attributed to the introduction of preventive measures

7. • to answer these questions hypothesis are formulated and
tested that may help to explain the situation
• Examples of analytical studies are :ecological ,cross-
sectional study, cohort study and case control study

8. • Ecological studies also referred as correlational studies
• The units of analysis are group of people rather than an individual
• Eg in one country a relationship was demonstrated between
average sales of anti asthma drugs and occurrence of asthma
• Can be done by comparing populations in different countries at
the same time or same population in one country in different time

9. Cross-sectional study
• Also known as prevalence studies , are carried out at a certain point
in a given population or geographical location
• They depends on a single examination of a crossectional area of the
population in which sick and health or exposed and unexposed are
not distinguished until results are examined
• Information is collected through survey by means of
questionnaire,laboratory or physical examination

10. • The prevalence of risk factors or diseases is expressed as
proportion of affected individual in the study population in
a given geographical area at a given point in time
• Its limitation is inability to state out cause effect
relationship since both are found at the same time

11. Cohort study
• Synonymous to prospective study, longitudinal, follow up or
incidence studies
• They can be carried out prospectively /historically (retrospectively)
• They are carried out on a sample of population to determine the
rate t which group of the population developed diseases when
differently exposed
• This is one way of testing hypothesis in disease causation

12. Case –control study
• Synonymous to case referent study
• This study involve comparison of cases of disease under
study with comparable controls for level of exposure
• The effect of exposure in such study is measured by odd ratio

13. THE END