Answer
Observational study.
A study in which the value of the response variable is to be calculated without affecting the value of any of the explanatory variables in the model is said to be an observational study.
Designed experiment.
An experiment in which the experimenter assigns the individuals into different groups to change the explanatory variables intentionally, and each group is examined differently, is a designed experiment.
A researcher would claim causation between the explanatory and the response variable in a designed experiment, which is not possible in an observational study.
Work Step by Step
Observational study
In an observational study, the experimenter has no hold over the response variable and no treatment is given to subjects to modify the explanatory variable. While conducting an observational study, no extra information is to be added to the data, and the data should be inferred the way it is collected.
Designed experiment.
Control and treatment are the two basic key features of any well-designed experiment. Experimenter assigns the individuals into different groups and intentionally changes the value of the explanatory variables and then records the value of the response variable for each group. A control group is never treated and remains as it is till the experiment is completed.
Designed experiment and observational study on the basis of causation.
Causation is one of the key features of any designed experiment. It means that casual inferences or conclusions between the explanatory and response variables are drawn only in the designed experiment.
