1. Lecture 6 Psyc 300A

2. Agenda Quiz 3 Homework discussion Review from last week Overview of tonight: Variables

3. Measuring Variables Hypothetical construct –An abstract concept made up of components that relate to one another and help explain behavior –Can’t be measured directly Variable –A characteristic that can be measured –Can take on more than one value –Component of a hypothetical construct –Remains hypothetical until it is operationalized

4. Measuring Variables (continued) Operational definition –Variable is defined by how it is measured –Operationally defined variable can be directly measured –Process is called “operationalizing” a variable

5. Relationship Between Constructs, Variables, and Operational Definition Hypothetical Construct Variable 1 OD Variable 2 OD Variable 3 OD

6. Group Activity: Creating Variables and Operational Definitions Create variables and operational definitions for the following constructs: –Health –Sense of humor –Anxiety –Volunteerism

7. Scales of Measurement Nominal (categorical) Ordinal (ranked) Interval (interval between scores is meaningful. No absolute zero) Ratio (interval, but with absolute zero point)

8. Putting Constructs and Scales of Measurement Together What is the relationship between ethnicity and religiosity? What is the effect of exercise on health status?

9. Extraneous Variables and Confounds Extraneous variable –A variable that could influence the outcome of the study, but is not one of the variables of interest (not controlled) Confound/Confounding/Confounded Variable –An extraneous variable that varies systematically with the IV –Makes it impossible to know if IV caused change in DV

10. Group Exercise: Identifying Extraneous and Confounding Variables A group of researchers wanted to know whether ignoring political issues and attacking a candidate personally helps or hurts a political candidate’s chances of winning an election. They brought a group of students into a laboratory. Some students listened to an incumbent candidate laying out a specific plan to deal with political problems and issues. The other participants were exposed to a challenger who spent time talking about personal problems of the incumbent and why the challenger would bring greater morality to public office. The participants rated the candidate regarding the likelihood that they would vote for the person whose message they had just heard. (from Beins, p. 48)