BHS Methods in Behavioral Sciences I April 7, 2003 Chapter 2 – Introduction to the Methods of Science

The Research Cycle  Research begins with naturalistic observation. Observe and describe what occurs.  What are the relationships among observed variables? Correlational studies.  What are the causes and effects? Interact directly with variables – manipulate them in experiments that make predictions.

Additional Methods  Modeling – developing a mathematical or conceptual description of behavior. Test the model by comparing its performance to observed behavior.  Qualitative methods – emphasize the subjective experience of the participant. Interviews, survey research, participant observation – BHS 205.

Definitions of Terms  Hypothesis – the idea being tested in a particular experiment. Expressed in terms of the manipulation. Derived from theory (which is general).  Experimental group – the group that receives the treatment.  Control group – a group that is treated similarly in all respects but gets no treatment.

More Definitions  Independent & dependent variables (see last week’s lecture).  Treatment effect – the difference in the size of the dependent variable when comparing the treatment and control groups.  Confounding variables (“confounds”) – unintended independent variables that also change the dependent variable. Alternative explanations for the results.

Exploratory Research  Hypothesis testing is best used when something is known about a phenomenon.  Exploratory research is used when less is known. Used when effects of the independent variables cannot be predicted. Can involve manipulations and control groups, or not.

Validity  Are our statements about a phenomenon true and capable of being supported?  Internal validity – can we draw the conclusion we wish from our study or might something else explain the results? Internal consistency and logic of the experiment.  External validity – can we apply the results of a particular experiment to the world at large? Generalizability of the experiment.

Logic of Experimentation  Two forms of logic: Deduction – moving from general principles to specific conclusions. Induction – moving from specific observations to general principles.  Induction is used during naturalistic and exploratory research.  Deduction is used during experiments.

Propositional Logic  Modus Ponens (confirmatory) If p then q Observe p Conclude q  Modus Tollens (disconfirmatory) If p then q Observe not-q Conclude not-p

Logical Fallacies  Affirming the consequent If p then q Observe q Conclude p  Denying the antecedent If p then q Observe not-p Conclude not-q