Answer:
The main difference between an observational study and an experiment is the inclusion of a random sample.
Step-by-step explanation:
In an observational study, the researchers do not interfere with the method the data is collected. In an investigation of how regularly the studying improves marks, the researchers sample people from the population who has studied regularly and those who haven't and then collect the average marks obtained by each of the groups. We can only accomplish an association among the response variable and the explanatory variables because there may be some other variable that may affect both the explanatory and the response variable, thus making it look as if there is a relationship among them.
But in an Experiment, the researchers actually interfere with the method the data is collected. In an experiment, each case is randomly assigned to the treatment groups, i.e. to say that each of the cases has an equal chance of being in both groups. These kinds of studies help us to establish causal connections between the response variable and the explanatory variables because random assignment makes sure that they are equally spread among both the groups.
So, the primary difference between an observational study and an experiment is that in case of an observational study there is no random assignment but in case of an experiment there is a random assignment.
