Experimental studies, also called interventional studies, are studies where the researcher arranges the conditions in which the participants are placed, or conducts an intervention on them to assess its impact and consequences and test a hypothesis. In experimental studies, the researcher has control over the specifics of an intervention, who is the target of the experiments, and who is excluded. This allows experimental studies to be more precise in their results, and significantly reduce the number of irregularities by accounting for the majority of the factors in play.
One of the principal difficulties of using experimental studies is the questions of ethics. While the researcher has control over the conditions of the experiment, it is ethically wrong to expose subjects to potentially hazardous conditions, even for the purpose of betterment of healthcare and epidemiology of public health. This limits the use of experimental studies to patients already afflicted with problems and puts the responsibility on the researcher not to harm his subjects through the research.
The difference between experimental and observational studies is that in the latter researchers do not intervene with their subjects and the conditions which impact them and limit their actions to the observation of variables of interest. Researchers often resort to observational studies when interventional studies would violate ethical standards, or when the researcher does not have the influence or the budget to conduct an experiment. Most researches assessing different nationwide issues are observational. For example, if a researcher needed to study the effects of political or healthcare legislation on the communities, it would be more efficient and productive to find communities that already have similar legislation instated, rather than organizing a sample team of communities and persuading the local or federal government to pass the regulation, as an experimental study would require. Finally, the study may be dependent on a lack of outside involvement to fulfill its purpose.
However, this also means that epidemiological phenomena that do not have analogs available for studies, such as new treatment methods or healthcare policies, cannot be effectively analyzed using the observation method. They can, however, help define the hypothesis that would be experimentally tested in future research.
In epidemiology and academia, the experimental studies are considered to be more factual and accurate, in many ways because they can be augmented by randomization and blinding. Randomization aims to reduce selection bias and maximize statistical power, by randomly allocating exposure to different groups and individuals, while evaluating them in the same way. The effects can be further augmented if the experiment is “blinded”, which means that information about the test is withheld from the subjects, in order to keep them unbiased. Blind testing is used in experiments where the participants’ (or even researchers) expectations and preferences can color the experience. For example, if a disease treatment is tested against a control group that is receiving no treatment, or receives placebo replacements, blinding can help the researchers better differentiate actual effects and side-effects of the treatment by comparing two reactions, and double-blinding (researchers not knowing which of the analyzed participants belong to which group), helps avoid researcher bias.
In conclusion, randomized double-blind experiments are considered the gold standard of scientific accuracy in epidemiology. Experimental study design should be used when maximum accuracy of conditions is needed to validate the purpose of the study, and when bias and confounding of unknown variables can adversely affect the vital treatment or a phenomenon analyzed.