Final answer:
In experimental design, the two main groups are the control group and the experimental group, with the control group often receiving a placebo to maintain experiment integrity and serve as a baseline for comparison.
Step-by-step explanation:
In an ideal experimental design, two groups of subjects are fundamental: the control group and the experimental group. The control group does not receive the experimental manipulation that the experimental group does. Instead, they may receive a placebo treatment to maintain experimental integrity. The primary purpose of the control group is to serve as a baseline for comparison, showing what happens when the variable being tested – the independent variable – is not applied. The outcomes measured in the dependent variable, after experimental manipulation, help researchers to understand the effects of the independent variable on the subjects. Experimental designs may employ random assignment to ensure that both groups are comparable and that any differences observed are due to the manipulation of the independent variable rather than other factors.
Rigorous experimental design, including the creation of clear control and experimental groups, allows researchers to avoid the pitfalls of relying on anecdotal evidence or limited personal observations for testing hypotheses. When designed properly, experiments can provide clear evidence to support or refute causal relationships.
Double-blind, randomized controlled trials are considered the gold standard in research, especially in medical fields where neither the researchers nor the participants know who is receiving the active treatment and who is receiving a placebo. This method is key in preventing biases that may skew the results.