AP PSYCHOLOGY

Detailed explanation-1: -Experimental research, often called true experimentation, uses the scientific method to establish the cause-effect relationship among a group of variables that make up a study.

Detailed explanation-2: -The use of a controlled study is the most effective way of establishing causality between variables. In a controlled study, the sample or population is split in two, with both groups being comparable in almost every way. The two groups then receive different treatments, and the outcomes of each group are assessed.

Detailed explanation-3: -What is correlational research? A correlational research design investigates relationships between two variables (or more) without the researcher controlling or manipulating any of them. It’s a non-experimental type of quantitative research.

Detailed explanation-4: -Answer and Explanation: The only method that will establish a cause-and-effect relationship is an experimental research design.