comer, abnormal psychology, 6th edition - midlands technical 来的人，心理异常，第六版-米德兰技术

Comer, Fundamentals of Abnormal Psychology, 3e,1,Chapter 2,Research in Abnormal Psychology,Slides & Handouts by Karen Clay Rhines, Ph.D.Seton Hall University,Comer, Fundamentals of Abnormal Psychology, 3e,2,What Do Clinical Researchers Do?,Clinical researchers try to discover laws and principles of abnormal psychological functioning:Search for nomothetic understanding: a general understanding of the nature, causes and treatment of abnormal behavior.Use the scientific method to pinpoint relationships among variablesThey systematically collect and evaluate information through careful observationUse three methods of investigation to form and test hypotheses,Comer, Fundamentals of Abnormal Psychology, 3e,3,The Case Study,Provides a detailed, interpretative description of a persons life & psychological problemsCan serve as a source of new ideas about behaviorFreuds theories based entirely on case studiesMay offer tentative support for a theoryMay challenge a theorys assumptionsMay inspire new therapeutic techniquesMay offer opportunities to study unusual problems,Comer, Fundamentals of Abnormal Psychology, 3e,4,The Case Study,Has limitations:Observers are biasedRelies on subjective evidenceHas low internal validityProvides little basis for generalizationHas low external validity: the degree to which the results of a study can be generalized to other people.These limitations are addressed by the two other methods of investigation,Comer, Fundamentals of Abnormal Psychology, 3e,5,The Correlational Method & The Experimental Method,Do not offer richness of detailDo allow researchers to draw broad conclusionsTypically involve observing many individualsResearchers apply procedures uniformlyStudies can be replicatedResearchers use statistical tests to analyze results,Comer, Fundamentals of Abnormal Psychology, 3e,6,The Correlational Method,Correlation is the degree to which events or characteristics vary with each otherMeasures the strength of a relationshipDoes not imply cause and effectThe people chosen for a study are its subjects or participants, collectively called a sampleThe sample must be representative,Comer, Fundamentals of Abnormal Psychology, 3e,7,The Correlational Method,Correlational data can be graphed and a “line of best fit” can be drawnPositive correlation = variables change in the same direction Negative correlation = variables change in the opposite direction Unrelated = no consistent relationship,Comer, Fundamentals of Abnormal Psychology, 3e,8,Positive Correlation,Comer, Fundamentals of Abnormal Psychology, 3e,9,Negative Correlation,Comer, Fundamentals of Abnormal Psychology, 3e,10,No Correlation,Comer, Fundamentals of Abnormal Psychology, 3e,11,The Correlational Method,The magnitude (strength) of a correlation is also importantHigh magnitude = variables which vary closely together; fall close to the line of best fitLow magnitude = variables which do not vary as closely together; loosely scattered around the line of best fit,Comer, Fundamentals of Abnormal Psychology, 3e,12,Magnitude of Correlation,Comer, Fundamentals of Abnormal Psychology, 3e,13,The Correlational Method,Direction and magnitude of a correlation are often calculated statisticallyCalled the “correlation coefficient,” symbolized by the letter “r”Sign (+ or -) indicates directionNumber (from 0.00 to 1.00) indicates magnitude0.00 = no consistent relationship+1.00 = perfect positive correlation-1.00 = perfect negative correlationMost correlations found in psychological research fall far short of “perfect”,Comer, Fundamentals of Abnormal Psychology, 3e,14,The Correlational Method,Correlations can be trusted based on statistical probability“Statistical significance” means that the finding is unlikely to have occurred by chanceBy convention, if there is less than a 5% probability that findings are due to chance (p .05), results are considered “significant” and thought to reflect the larger populationGenerally, confidence increases with the size of the sample and the magnitude of the correlation,Comer, Fundamentals of Abnormal Psychology, 3e,15,The Correlational Method,Advantages of correlational studies:Have high external validityCan generalize findingsCan repeat (replicate) studies on other samplesDifficulties with correlational studies:Lack internal validityResults describe but do not explain a relationship,Comer, Fundamentals of Abnormal Psychology, 3e,16,Comer, Fundamentals of Abnormal Psychology, 3e,17,The Correlational Method,Two special forms of correlational study:Epidemiological studiesReveal the incidence and prevalence of a disorder in a particular populationIncidence = number of new cases in a given periodPrevalence = total number of cases in a given periodLongitudinal studiesObserve one sample of participants on many occasions over a long period,Comer, Fundamentals of Abnormal Psychology, 3e,18,The Experimental Method,An experiment is a research procedure in which a variable is manipulated, and the manipulations effect on another variable is observedManipulated variable = independent variableVariable being observed = dependent variableAllows researchers to ask questions such as: Does therapy X reduce symptoms of disorder Y?Causal relationships can ONLY be determined through experiments,Comer, Fundamentals of Abnormal Psychology, 3e,19,The Experimental Method,Statistics and research design are very importantResearchers must eliminate all confounds those variables other than the independent variable that may also be affecting the dependent variableThree features are included in experiments to guard against confounds:The control group Random assignmentBlind design,Comer, Fundamentals of Abnormal Psychology, 3e,20,The Experimental Method,A control group is a group of participants who are not exposed to the independent variable, but whose experience is similar to that of the experimental groupBy comparing the groups, researchers can better determine the effect of the independent variableRules of statistical significance are applied,Comer, Fundamentals of Abnormal Psychology, 3e,21,The Experimental Method,Researchers must also watch out for differences in the makeup of the experimental and control groupsTo do so, researchers use random assignment any one of a number of selection procedures that ensures that every participant in the experiment is as likely to be placed in one group as anotherExamples: coin flip; drawing names from a hat,Comer, Fundamentals of Abnormal Psychology, 3e,22,The Experimental Method,A final confound problem is biasTo avoid bias by the participant, experimenters employ a “blind design,” in which participants are kept from knowing which condition of the study (experimental or control) they are inOne strategy for this is provi