1. Experimental Study

2. Experimental epidemiology
Prospective study
The randomly assigned subjects to either treatment or certain interventions are under the direct control of the investigator
The controls are assigned for comparison and assessing the effectiveness of interventions
It involves some action, intervention or manipulation

3. Aims
To provide "scientific proof" of aetiological factors which may permit the modification or control of the disease (s).
To provide a method of measuring the effectiveness and efficiency of health services/programs for the prevention, control and treatment of disease and improve the health of the community.
To study the efficacy and effectiveness of drugs/vaccines for the treatment and prevention of disease or health problems.

4. Study population (Sampling)
Sample population (randomization)
First data collection
(Same time as in study group)
Study group (experimental)
Control (comparison group)
(Before intervention)
Intervention / manipulation
No manipulation / intervention
Last data collection
(After intervention)
Compare

5. Experimental studies are conducted either in animal or humans.
Animal studies are used in anatomy, physiology, pathology, microbiology, immunology, genetics, chemotherapy etc.
Animal studies are used for
Experimental reproduction of human disease in animal to confirm aetiological hypothesis and to study the pathogenic phenomena or mechanisms
Testing the efficacy of preventive and therapeutic measures such as drugs and vaccines
Completing the natural history of disease

6. Human experiments are needed to investigate disease aetiology and to evaluate the preventive and therapeutic measure for that disease which cannot be reproduced in animal.
Experimental studies are of two types
Randomized controlled trails
II Non-randomized controlled trails

7. Randomized controlled trial
Randomized controlled trail (RCT) is scientific technique to evaluate method of treatment and prevention.
Steps of RCT
Drawing up a protocol
Selecting reference and experimental populations
Randomization
Manipulation and intervention
Follow up
Assessment of outcome

8. Drawing up a protocol
RCT is conducted under a strict protocol
The protocol should include
aims and objectives of the study
selection criteria of study and control group
detailed procedure
The protocol should be followed throughout the study

9. Selection of reference and experimental populations
i. Reference population
It is the population in which finding of trials, if successful, are applied.
Reference population may be board or limited specifically by geography, age, sex, occupation, social group etc.
ii. Experimental population
The study population is derived from the reference population to generalize the study findings to the target population.
They must give informed consent
They should be representative of the population
They should be qualified for the trail

10. The participants are randomly assigned into study and control group.
Study group is the group of individuals who are offered the new treatment, preventive agent or any type of intervention under investigation.
Control group is the group of individuals who are not offered the measure and receive the usual accepted treatment or placebo.

11. Randomization
Randomization is a process which gives the every subject equal chances to be selected for the study.
It is an attempt to eliminate bias and allow for comparability.
Randomization is the heart of RCT.
It works best when sample is large.

12. Randomization
process by which each participant has the same chance of being assigned to either intervention or control group
 assure the compatibility of characteristics among Treatment and Control group
eliminates the source of bias like investigator bias
facilitates blinding the type of treatments to the investigator, participants, and evaluators

13. Manipulation
It is the intervention stage, which is performed after the selection of study and control group.
Follow up
It is essential till final assessment of outcome.
During follow up, there may be attrition problem due to death, migration, and loss of interest.

14. Blinding is done to reduce bias in outcome assessment.
Assessment of outcome
The final step is assessment of the outcome in terms of positive and negative results.
Bias during assessment may be due to subject variation, observer bias and bias in evaluation.
Blinding is done to reduce bias in outcome assessment.
In single blind trial, the participant is not aware whether belongs to the study group or control group.
In double blind trial, both the doctor or study team member and participants do not know the group allocation and treatment received.
In triple blind trial, the participants, investigator and analyzer are all blind.

15. Example of therapeutic trials
Clinical trials
Example of therapeutic trials

16. Example of preventive trials

17. Community trials Kabilasi VDC Chandra nagar VDC
Baseline sandfly number by CDC light trap
Random assignment for IRS, LLINs, and control
Intervention and monitoring of kala-azar cases, sandfly number
Reduction in kala-azar cases and sandfly number

18. Blinding
procedure that prevent study participants, caregivers, or outcome assessors from knowing which intervention was received
3 types
Single blind - participants are not aware of treatment group
Double blind - both participants and investigators unaware
Triple blind – participants, investigators and the person reviewing the data are all masked.

19. Advantages
Other study designs can also detect associations between an intervention and an outcome. But they cannot rule out the possibility that the association was caused by a third factor linked to both intervention and outcome.
It controls selection bias and confounding bias.
Facilitates effective blinding.
Carries strong evidences than any other studies (plausibility).
It also maintains the advantages of cohort studies.

20. Disadvantages May be complex and expensive
Difficult and expensive with low incidence outcomes
May lack representativeness - volunteers may differ from population of interest
Ethical challenges of experimental research
Sometimes impossible or impractical to conduct

21. Ethical consideration
Is it ethical to randomize?
Is it ethical not to randomize?
Is it ethical to use a placebo?
Another important question is whether truly informed consent can be obtained?
Under what circumstances should a trial be stopped earlier than originally planned (either harmful effects or beneficial effects of the agent become apparent early)

22. The study is not a true or actual experiment.
Quasi-experiment
In some experiments, the investigator might not be able to randomized subjects into treatment and control groups due to some certain constraints.
The study is not a true or actual experiment.
Study group
after
Control group
Compare
before
Intervention