Experimental Research Designs
Experimental research comes in different types, each with specific strengths and applications. True experimental designs include all three characteristics: manipulation, control, and randomization.
The pre-test post-test control group design is the most common approach, where you measure both groups before and after treatment. Even more rigorous is the Solomon Four Group Design—considered the most credible since it minimizes threats to validity by using four randomly assigned groups with different combinations of pre-tests, treatments, and post-tests.
When you can't fully randomize or control all variables, quasi-experimental designs step in. These still involve manipulation but might lack randomization or control groups. The nonrandomized control group design and time series design are common examples that let you study interventions in real-world settings.
Remember: The more control you have over your experiment, the stronger your ability to establish cause and effect relationships.
For preliminary exploration, pre-experimental designs offer options when you have limited control. These include one group pre-test/post-test designs and one-shot case studies. While these designs lack internal validity controls, they can serve as valuable trial runs before more rigorous research.
As you choose your research approach, consider what level of evidence you need and what controls are practical in your specific situation.