N goal of quantitative/ psychology is the explanation of behaviour. Scientific method agreed-upon approach to discovery and explanation. N: set of rules that dictate general procedures a scientist must follow in research, rules are based on logic and common sense. N naturalistic observations observation of behaviour of people or animals in their natural environment: least formal and constrained by fewest rules, provide foundation of biological and social sciences. N correlational studies examination of relations between 2+ measurements of behaviour or other characteristics of people or animals. Involve more formal measurements of environmental events, of individuals" physical and social characteristics, and of their behaviour. Experiments study which researcher changes value of an independent variable and observes whether this manipulation effects value of dependent variable: only research which can confirm existence of cause-and-effect relations among variables. Five steps summarizing the rules of scientific method: identify the problem and formulate hypothetical cause-and-effect relations among variables.