The essence of an experiment, as opposed to an observational study is to:

a. change one or more factors and observe the effects

b. reduce the number of hidden variables

c. base findings on a facts that can be observed and verified.

d. start with a hypothesis and prove or disprove it

The correct answer to the question: The essence of an experiment, as opposed to an observational study is to:___, would be, A: change one or more factors and observe the effects.

Explanation:

In research, there are many ways in which anyone can hypothesize a theory, and test it to prove, or disprove it. But depending on the purpose of the research, meaning what is expected to be obtained from it, the type that will be selected to be applied may vary. Essentially, observational studies are once in which a thesis is created and then it is tested through observation of a selected sample of subjects to study, but without affecting any of the factors around the subject. The researcher only wants to observe how a subject of study acts, or reacts, in his/her or its natural environment without interference. However, when the desire is to compare, or test the differences between things, when applied to groups of selected subjects, then we are talking about a more controlled type of study and this is called an experiment. The main difference between experiments and observational studies is that in experiments what the researcher does is to change factors in order to observe the effects; in the observational study, this does not happen. This is why the answer is A.