Chapter 1: Psychology as a science The scientific method: Observation => Theory (broad framework) => Hypothesis (testable prediction) => Study => Observation Research methods:      Natural observation: externally valid and behavior in context, but ethical issues and lack of control.      Case studies: can study very unusual thing, but problem of generalization.      Survey: can study things that we cannot observe otherwise, but there may be interpretation problems.      Correlation: relation between variables,           positive correlation means variables vary in the same direction,           negative correlation means variables vary in opposite directions,           cannot infer causation because of potential third variable and directionality of cause.      Experimentation:           Independent variable: the variable we vary => can infer causation; need three levels to detect potential non-linear effects.           Dependent variable: our measure.           Low external validity.