This document describes four types of quantitative research based on variables and subjects studied: descriptive research looks at multiple variables like intelligence and computer use among a group; correlational research examines the relationship between two variables like computer use and literacy among secondary school students; causal-comparative research looks at the effect of a non-manipulated independent variable like mother tongue on a dependent variable like math scores for a group; experimental research determines the effect of a manipulated independent variable like an ethics program on a dependent variable for subjects.