I. Theory Building

All of the information in your book is based scientific research studies derived from theories…

• Theory: An integrated set of underlying principles that explain a set of observations and that can be used to deduce a large number of hypotheses (i.e. testable predictions)
• Qualities of a good theory…
• Makes predictions, not postdictions
• Predicts one outcome, not many
• Makes specific, not vague, predictions
• Makes verifiable predictions
• Hypothesis: A testable, operationally-defined prediction about the relationship between two or more variables
• The hypothesis sets up the main premise of the theory which can be validated or contradicted by other researchers

A. Experimental Design: Controlled situations in which independent variables are manipulated to observe the effects (i.e., changes) on the dependent variables

• Independent variable: The variable in the experimental design that is intentionally manipulated
• The “cause” in the “cause-and-effect” relationship between two variables in a hypothesis
• Dependent variable: The variable in the experimental design that is measured after an independent variable is changed
• The “effect” in the “cause-and-effect” relationship
• The hypothesis predicts that the dependent variable will be changed as a result of changing the independent variable

• Experimental Group: Set of participants who experience the hypothesized “cause”
• Control group: Set of participants who are treated exactly the same way as the experimental group but do not experience the hypothesized “cause

• Confounding Variables: uncontrolled, and unaccounted for, variables (alternative “causes”) that affect the dependent (measured “effect”) variable along with (or in place of) the independent variable (hypothesized “cause”) of interest
• Bias: Previous beliefs, expectations, or habits alter the participants’ responses
• Response bias: when participants’ biases affect the results of the study over and above (or in place of) the hypothesized “cause”
• Experimenter bias (aka “experimenter expectancy effects”): when the experimenter’s biases affect the results of the study
• Construct Validity: A measure or manipulation is valid if it does in fact measure or manipulate what it is supposed to measure/manipulate