Textbook Notes (368,544)
Canada (161,960)
Psychology (9,695)
PSYB01H3 (581)
Chapter 8

Chapter 8

4 Pages
Unlock Document

David Nussbaum

Chapter 8: Quasi Experimental and Non-experimental Designs  Randomization is what make experiments true Quasi Experimental Design  When we cannot directly manipulate an independent variable  Subject variables: type of an independent variable; particular individual characteristics that cannot be manipulated and instead must be selected; ex. Gender, history, traits, locale etc  Natural treatment: when exposures to events situations or setting that emanate from the real world define how participants are selected; levels are exposure and non exposure; ex historical events, natural disasters, policy changes  Quasi experiment: one that investigates the effects of a quasi-independent variable on a dependent variable o Nonequivalent-control-group design: have experimental and comparison groups that are designated before the treatment occurs and are not created by random assignment o Before and After Designs: have a pre-test and a post test but no comparison groups participants; the participants exposed to the treatment were at an earlier time their own controls  Other quasiexperimental designs similar to this: interrupted-time-series design, multiple-group before-and-after design, repeated-measures-panel designs o There are more kinds as well Natural Treatments as Quasi-Independent Variables o Ex post facto: analysis, after the fact analysis of its affect on particular dependent variable Subject Variables as Quasi-Independent Variables o Can combine quasi-independent variables and manipulated independent variables o Mixed factorial design: combines both between- and within-subjects factors Nonequivalent-Control-Group Designs o As its not random assignment control group cannot be considered equivalent to experimental group o Have high external validity and ecological validity in particular Matching o Individual matching: individuals in treatment group are matched with similar individuals in the control groups o Aggregate matching: identifying a comparison group that matches the treatment group in the aggregate o NOTE: individuals must not be able to choose which group they are in o Regression artifact: statistical phenomenon that can occur anytime a pretest measure is used  Regression to the mean: when compare groups regardless of any kind of intervention people who received extreme scores on a test of ability when retested on that same ability earn scores that are closer to the mean of their group than were their original scores  Confounding factor for interpreting results of studies that match groups on pretest measures Before-and-After Designs o Useful for studies of interventions that are experienced by every case in the population o Fixed-sample panel design: simplest; see Chapter 5 o Interrupted-time-series design: single experimental group for which multiple observations are taken before and after a naturally occurring treatment ex. Public policy change  Have to know when time series is interrupted by natural occurring treatment  Ex. Suicide rates and discouraging use of antidepressants o Multiple group before-and-after design: several before and after comparisons are made involving the same independent and dependent variables but with different groups o Repeated-measures panel designs: involves multiple pretest and posttest observations of the same group; allow study of impact over time o Time-series design: involve many observations in both pretest and posttest periods; disparity between preintervention trend and postintervention trend is evidence that intervention had an impact; useful in studying new laws or social programs A Quasiexperiment of Memories of 9/11 o Functional magnetic resonance imaging (fMRI): uses blood oxygen dependent level signal (BOLD) signal to measure brain activation while participants perform various tasks Experimental Stimuli and Task o Experimental stimuli were word cues ex. Morning, New York City, lunch, evening , weather; recorded brain response to these words and then rated each word on arousal, vividness, reliving, remember/know, confidence and valence o Two experimental conditions: September 2001 and summer 2001 and same words in each condition Ex Post Facto Variables and Comparison Groups o Created comparison groups of distance away from towers ex post facto to account for differences seen in ratings of memories o Recollective experience enhancement: a new subject variable from the combination of the 6 characteristics Correlational Relationships o Has low internal validity lessening confidence in causal conclusions o Correlation coefficient: statistic that tells the degree and direction of a relationship between two variables o Scatter diagrams: graph of a correlation involving two variables o Amygdala: almond shaped structure deep in the brain that plays a key role in fusing memories
More Less

Related notes for PSYB01H3

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.