Question

_____ involves a type of quantitative research that systematically manipulates one or more variables to determine which variables have a causal effect on other variables.

Answer 1

Experimental research involves a type of quantitative research that systematically manipulates one or more variables to determine which variables have a causal effect on other variables.
This way, you determine whether your hypothesis was correct, by conducting an experiment to test your thesis. You change things up to see if you were right or wrong during an experimental research.