Final answer:
Case studies typically do not involve experimental manipulation and are considered observational studies. They observe natural settings without intervention, unlike true experimental designs and factorial designs, which involve manipulating variables to determine effects.
Step-by-step explanation:
The method of research that typically does NOT involve experimental manipulation is B. Case studies. Case studies are considered to be an observational study method wherein detailed investigations are conducted on a single individual, group, event, or community. Case studies do not manipulate variables but instead observe them in a natural setting without intervention.
On the other hand, A. True experimental designs and C. Factorial designs both involve manipulation of variables to test the effects on an outcome. True experimental designs are characterized by random assignment and control of variables, providing a high level of evidence for causal relationships. Factorial designs are used to explore the interaction effects between two or more independent variables, also involving experimental manipulation.
When it comes to designing scientific experiments, it is important to correctly identify components, such as the population, sample, experimental units, explanatory variable, treatment, and response variable. In the given example of a study regarding the size of tableware influencing college students' food consumption, the population might be all college students, the sample is the 100 college students chosen for the study, the experimental units are the individual students, the explanatory variable is the size of tableware, the treatment is the use of normal-sized or smaller tableware, and the response variable is the amount of food consumed.
Experimental design involves a careful setup including a control group and an experimental group. Only the experimental group receives the experimental manipulation, while the control group does not.