Types of Experimental Research
Experimental research isn't one-size-fits-all - it comes in several varieties with different levels of scientific rigor. Understanding these differences helps you evaluate research validity!
True Experimental designs include all three essential characteristics: manipulation, control groups, and randomization. The Solomon Four Group Design is considered "the most credible" since it minimizes threats to both external and internal validity by controlling for testing effects.
Quasi-Experimental designs lack either randomization or control groups but still involve manipulation of variables. These designs are practical when true randomization isn't possible, such as in classroom settings where students can't be randomly assigned. Types include nonrandomized control group designs and time series designs.
Pre-Experimental designs offer the researcher minimal control over the experiment and variables. They provide little protection against threats to internal validity but can serve as valuable trial runs. Common types include one group pre-test/post-test designs and one-shot case studies.
Remember: The more control elements (manipulation, control groups, randomization) your design includes, the stronger your ability to establish causation rather than just correlation!