2. EXPERIMENTAL EPIDEMIOLOGY
INTERVENTION STUDY
EXPERIMENTAL STUDY
RANDOMIZED CONTROLLED TRIALS
In which experiment or trials are made and results are watched.

3. EXPERIMENTAL STUDIES
Experimental studies are similar in approach to cohort studies excepting that the conditions in which study is carried out are under direct control of the investigator.

4. EXPERIMENTAL STUDIES
Involve some action, intervention or manipulation:
Application of a drug, vaccine
Withdrawal of certain factor
Changing one variable in exp. group and no change in control group & then observing &comparing the out come of two groups

5. EXPERIMENTAL STUDIES
The researcher manipulates a situation and measures the effects of the manipulation. Usually two groups are compared, one in which the intervention takes place (treatment with a certain drug) and the other remains untouched (treatment with a placebo).

6. AIMS OF EXPERIMENTAL STUDIES
To provide scientific proof of aetiological factors which may permit modifications or control of those diseases.
To provide a method of measuring the effectiveness and efficiency of health services for prevention, control and treatment of diseases and improve the health of the community.

7. ANIMAL STUDIES Contributed to our knowledge
Reproduction of human diseases in animals to confirm aetiological hypothesis, mechanism of disease occurrence
Testing the efficacy of preventive and therapeutic measures e.g. vaccine, drugs
Completing the natural history of diseases

8. ANIMAL STUDIES ADVANTAGES: LIMITATIONS:
animals can be bred in laboratories and manipulated easily a/c to wishes of the investigator
Animals multiply rapidly and enable the investigator to carry out experiments
LIMITATIONS:
Not all human diseases can be reproduced in animals
Conclusions derived from animal experiments may not be applicable to human beings.

9. EXPERIMENTAL STUDIES
Most incisive approach to scientific problem, the only study that can prove causation.
Ethical problems, Logistic considerations
Benefits of the study must be weighed against risks
Persons involved in research must be fully informed about all possible consequences of the experiment.

10. Steps in Experimental Study
1. Drawing up of a protocol
2. Selection of reference and experimental population
3. Randomization
4. Manipulation or intervention
5. Follow up
6. Assessment of outcome

11. 1.Drawing up of a protocol
To specify aims and objectives of the study
Questions to be answered
Criteria for the selection of study and control group
Size of the sample
Procedures for allocation of subjects into study and control groups
Action, treatment to be applied
Schedule and evaluation of outcome of the study
Protocol must be adhered throughout the study.

12. 2. Selection of reference & experimental population
Reference or target population
Population in which findings of trial are expected to be applicable
Experimental or study population
Derived from reference population
Randomly chosen group from reference population
Chose a stable population
Informed consent
Representative of the population
Eligible for the trial

13. 3. RANDOMIZATION
A statistical procedure by which participants are allocated into groups i.e. study and control to receive or not to receive a preventive, therapeutic procedure or intervention.
Each subject is given an equal opportunity/chance of being assigned to either group and blindly selecting the numbers for each group.
Randomization allows comparability and eliminates errors.

14. Manipulation Intervene or manipulate the study group
Application of
Withdrawal of
Reduction of suspected causal factor
Independent variable whose effect is determined by measurement of final outcome that constitutes the dependent variable.

15. Follow up Examination of control and study groups at regular intervals
Standard manner
Equal intensity
Same conditions
Duration must be sufficient to demonstrate a significant difference
Follow up may be short or long
Minimize the losses to follow up.

16. Assessment Positive results Negative results
Comparison of results in both groups
Differences are tested statistically
ERRORS
Subject variation
Observer variation
Bias in evaluation

17. BLINDING
The concealment of group assignment from the knowledge of the patients and/ or investigators in a clinical trial.
Blinding eliminates possibility
The knowledge of assignment may affect patient response to treatment
The Investigator’s behaviour that may affect outcome

18. SINGLE BLIND TRIAL
The participant is not aware whether he belongs to a study or control group
Knowledge of group assignment is with held only from patients.

19. DOUBLE BLIND TRIAL
The trial is so planned that neither the doctor nor the participant is aware of the group allocation and treatment received
Knowledge of group assignment is with held from patients and investigators

20. TRIPLE BLIND TRIAL
The participant, the Investigator and the person analyzing data are all blind.
Knowledge of assignment is with held from patients, investigators and analyst.

21. Experimental study

22. Quasi-experimental study design
Study Group
Before Intervention study group
after
Compare
Control group
Before control group

23. SELECTION OF STUDY DESIGN
Type of information you want to obtain
Devise strategies to enable to obtain that information.
The selection of an appropriate study design depends on:
The state of knowledge about the problem
The nature of the problem and its environment.
The resources available for the research
Objectives of the study.

24. CASE
A person who has a particular disease, health disorder or condition which meets a set of diagnostic criteria to be regarded as a case of disease and for surveillance and outbreak investigation purpose.