Interpreting and Generalizing your Results

Psych 231: Research Methods in Psychology

Announcements

This week in labs: POSTER SESSIONS Jen has final papers available at her office

hours (not in class today) Amanda’s may be done by labs this week

Research Results

Goal of Research– Experiments:

• To establish a cause and effect relationship between independent and dependent variables

– Correlational studies• To determine potential relationships between different

variables

Interpretation of your results

Statistical significance– Tell us if differences or (relationships with

correlations) go beyond what we’d expect by chance

– Don’t tell us anything about what the result really means in theoretical terms

Interpretation of your results

Theoretical Significance– Return to your theory(ies)

• Reject them? • Support (not prove) them?• Revise them?

– What are the limitations of your interpretations?• Are there alternative theories still to test?

– Yes, there are always going to be alternatives (not always good ones)

• Do your results generalize well?

Generalizing results External validity revisited

– What limits/constraints were imposed because of:• the use of experimental control• availability of resources

– Participant factors (who did you test?)• Volunteers • College students• Sex• Culture

– Location/setting factors (where did you test?)• College• Region• Laboratory

Generalizing results– Experimenter factors

• Personality, sex, experience as experiementer

– Experimental items• Do the results only apply to the stimuli that you used, or would

they extend to others– E.g., memory for:

» cat, dog, truck, car, … all concrete objects– Would the same pattern of results be seen for:

» call, dig, truth, cut, … more abstract concepts» cath, dob, trush, caf, … all non words

Threats to external validity as interactions

Generalization as interactions– Does your theory (or anyone else’s) predict an

interaction?– If you collect the appropriate data/controls, you

can do some statistical tests

In defense of college students

Convenient? – Yes, but not because researchers are lazy– Researchers do have limited resources

Criticisms about generalizability need to be backed up with theory and/or data

College students are after all humans Replications with other samples provide a safegaurd

against limited generalizability

Replications Importance of replications

– Demonstrate that the results weren’t a “one time” thing

• Single failure to replicate - don’t panic• Repeated failure to replicate - original results probably

wrong (maybe a Type I error)

Replications Types of replications

– Exact replications• Replication of the research as precisely as possible

– Conceptual replications• Same independent variables, but measured in a

different way– Same conceptual variables, different operational variables

Increasing External Validity Aggregation

– Grouping together data• Over participants• Over stimuli or situations• Over trials or occasions• Over measures (converging operations)

Increasing External Validity Non-reactive measurements

– Unobtrusive measures• Observation without participant awareness

– Naturalistic observation• To validate experimental findings

– Field experiments• Experimentation outside of the lab

Example

Results from Lab studies– Self awareness reduces likelihood of people

engaging in socially undersirable behaviors (e.g., cheating or lying)

Beaman, Klentz, Diener, & Sanum (1979)

“Hi, what’s your name?”

“Hi, what are you dressed as?”

Please take only one piece of candy

The big picture

Generalizing your to the outside world– The bottom of the hourglass– How do these results impact …– Not always stated in the report– But, should always be in the back of your mind.

• why are you doing the research? • why is it important? • who will benefit from this research?

Next time

Review of course