Experimental research is any research conducted with a scientific approach, where a set of variables are kept constant while the other set of variables are being measured as the subject of experiment change. Experimental research is the gold standard for investigating causal (cause/effect) relationships empirically. You can use experimental research to compare one group to itself over time or two groups two each other. In all designs, independent variables (X) are manipulated to see if it the change or difference between the samples (or groups) has an effect on the dependent variable (Y), generally using t-tests (see statistics). In contrast, an observational study does not involve experimental manipulation.
Experimental research is used to test hypotheses. A hypothesis is a testable statement that is formulated by the researcher to confirm a theory or address a specific question. The researcher’s job is to design an experiment that will support or disprove the hypothesis.