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Diagnosis, Classification, Research Methods and Abnormal Psychology

Diagnosis, Classification, Research Methods and Abnormal Psychology. Chapter 3. Diagnosing Psychological Disorders: Foundations in Classification. Clinical Assessment vs. Psychiatric Diagnosis Assessment – Idiographic approach Diagnosis – Nomothetic approach

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Diagnosis, Classification, Research Methods and Abnormal Psychology

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  1. Diagnosis, Classification, Research Methods and Abnormal Psychology Chapter 3

  2. Diagnosing Psychological Disorders:Foundations in Classification • Clinical Assessment vs. Psychiatric Diagnosis • Assessment – Idiographic approach • Diagnosis – Nomothetic approach • Both are important in treatment planning and intervention • The Nature and Forms of Classification Systems • Classical (or pure) categorical approach – Strict categories • Dimensional approach – Classification along dimension • Prototypical approach – Combines classical and dimensional views • DSM-IV and ICD-10

  3. Purposes and Evolution of the DSM • Purposes of the DSM System • Aid communication, evaluate prognosis, need for treatment, and treatment planning • Basic Characteristics • Five axes describing full clinical presentation (person and environment) • Clear inclusion and exclusion criteria for disorders, including duration • Disorders are categorized under broad headings • Prototypic approach to classification; one that is empirically grounded

  4. Basic Components of Research Study (cont.) • Internal vs. External Validity • Internal validity – Confidence that effects are due to the independent variable • External validity – Extent to which the findings are generalizable • Ways to Increase Internal Validity by Minimizing Confounds • Use of control groups or statistical control • Use of random assignment procedures • Use of analog models • Relation Between Internal and External Validity

  5. Types of Research Designs • Descriptive designs • Involves measurement of independent variables, but not manipulation by experimenter • Answers questions about relations among variables • Does not allow us to infer causation • Examples: case studies and epidemiology • Experimental designs • Involves manipulation of an independent variable to observe the effect • Allows stronger inference about causation • Examples: analog studies and randomized trials

  6. Basic Components of Research Study (cont.) • Internal vs. External Validity • Internal validity – Confidence that effects are due to the independent variable • External validity – Extent to which the findings are generalizable • Ways to Increase Internal Validity by Minimizing Confounds • Use of control groups or statistical control • Use of random assignment procedures • Use of analog models • Relation Between Internal and External Validity

  7. Descriptive Designs: Case Studies • Nature of the Case Study • Extensive observation and detailed description of a client • Foundation of early historic developments in psychopathology • Limitations of the Case Study • Lacks scientific rigor and suitable controls • Often entails numerous confounds • Useful for generating scientific hypotheses, but not testing

  8. Descriptive Designs: Epidemiology • Study incidence, prevalence, and course of disorders and disease • Uses “correlational method” • The Nature of Correlation • Statistical expression of covariation between two variables • No independent variable is manipulated • Nature of Correlation and Strength of Association • Range from –1.0 to 0 to +1.0 • Positive vs. negative correlation • Correlation and Its Relation to Causation • Problem of directionality • “Third variable” problem • Correlation does not imply causation

  9. Experimental Designs: Analog Studies • Experimenter manipulates independent variable to create phenomena analagous to psychological disorder • Animal models – depression, aggression • May be used to test treatment mechanisms or effects of psychological disorders • Advantage: larger potential samples • Disadvantage: limited external validity to clinical samples

  10. Experimental Designs: Randomized Trials • True experiment • Participants randomly assigned to experimental or control group • Independent variable is present in experimental group, absent in control group • Example: treatment outcome studies • Other considerations • Placebo can control for participant expectancy effects • Double-blind design can control for experimenter expectancies

  11. Studying Change over Time • How does the problem or behavior change over time? • Important in prevention and treatment research • Cross-sectional designs • Assess different groups of age cohorts at one time • Advantage: faster • Disadvantage: cohort effects limit inference of causes • Logitudinal designs • Follow one group over time, across different ages • Advantage: better inference about causes • Disadvantage: cross-generation effects limit generalizability

  12. Ethics in Research • Sources of Ethical Guidelines • Institutional Review Boards • APA Ethics Codes • Federal Regulations • Considerations • Informed consent – Historical evolution post WWII • Competence – Ability to provide consent • Voluntarism – Lack of coercion • Full information – Necessary information to make an informed decision • Comprehension – Understanding about benefits and risks of participation

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