Final answer:
Experimental research is a scientific investigation under controlled conditions where one or more variables are systematically manipulated to study their effects, which is typically quantitative in nature.
Step-by-step explanation:
Experimental research is a type of scientific investigation that is performed under controlled conditions. It often involves the manipulation of an independent variable to observe effects on a dependent variable, thus allowing researchers to draw conclusions about cause-and-effect relationships. In the context of the given question, the statements that apply to experimental research are:
- Systematically manipulates one or more variables: This is the core characteristic of experimental research. By changing one or more variables while keeping others constant, researchers can investigate causal effects.
- Quantitative research: Experimental research often results in numeric data that can be analyzed statistically. This contrasts with qualitative research, which deals with non-numeric data such as themes and experiences.
It is important to note that experimental research could also incorporate qualitative measures, though it is generally considered quantitative. Additionally, while experiments can be observational to some extent, 'usually observation' doesn't accurately describe the primary nature of experimental studies, which is to manipulate variables. Lastly, experimental research does not specifically determine the economic effect of constants in the market; this is a more specialized application that doesn't represent experimental research as a whole.