Correlational research is a non-experimental method that studies the relationship between two variables. It establishes whether and how two variables are related without manipulating the variables. There are three types of relationships: positive correlation, negative correlation, and zero correlation. The strength of a relationship is measured on a scale from -1 to 1. Correlational research is non-experimental, backward-looking as it analyzes past data, and dynamic as the relationships between variables can change over time.