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Quantitative Research Methods

Quantitative Research Methods. Richard Gramzow. Research Cycle. Theory Intuition Observation Consensus. Hypothesis (Conceptual). Method (Operational). Data Analysis (Statistical). Conclusion (s). Overview of Semester 1. Correlational Research Designs Descriptive Statistics

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Quantitative Research Methods

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  1. Quantitative Research Methods Richard Gramzow

  2. Research Cycle • Theory • Intuition • Observation • Consensus Hypothesis (Conceptual) Method (Operational) Data Analysis (Statistical) Conclusion (s)

  3. Overview of Semester 1 • Correlational Research Designs • Descriptive Statistics • Statistical Inference • T-tests, confidence intervals, power, and effect size • Bivariate Correlation • Bivariate Regression • Partial Correlation/Multiple Regression

  4. Basic Concepts: Correlational Research • Research Question • Hypotheses • Independent and Dependent Variables • Variables at the Conceptual Level • Operationalized Variables • Scales of Measurement • Causal Inference • Reliability • Construct Validity • Practical: Data Exercise Break

  5. Target Article • Are self-enhancing cognitions associated with healthy or unhealthy biological profiles? • Taylor, S. E., Lerner, J. S., Sherman, D. K., Sage, R. M., & McDowell, N. K. (2003). • Journal of Personality and Social Psychology, 85, 605-615.

  6. Research Question • Broad issue or problem • People tend to report overly positive self-evaluations • Are positive illusions about the self healthy or unhealthy? • Background • Falsely positive views of one’s medical condition (and personal control) are correlated with physical health and longevity • HIV/AIDS • Specific Question • Are self-enhancing cognitions associated with physiological indicators of stress regulation in healthy adults?

  7. Hypothesis • Statement about the presumed relationship among a set of variables • At the conceptual level • Self-enhancing cognitions reduce physiological responses to stress, resulting in: • Chronically better regulated stress systems • Lower acute responses to stress

  8. Where Do HypothesesCome From? • Bill McGuire (Annual Review of Psychology, 1997) • 49 Heuristics for Generating Hypotheses • Ranging from… • Statistical modeling to… • Disrupting ordinary states of consciousness.

  9. Where Do HypothesesCome From? • Inductive Techniques • specific observations lead to general hypotheses • Observe: Public, Self, Friends, Children, Pets • Case Studies • résumé embellishment • Paradoxical Incidents • Kitty Genovese • Practitioner’s rule of thumb • scarcity effect

  10. Where Do HypothesesCome From? • Deductive Techniques • reasoning from the general to the specific • Reasoning by analogy • inoculation and persuasion • Functional analysis • sex differences in jealously • Hypothetico-deductive method • Positive Illusions framework

  11. Hypotheses Independent Variable - The Cause. The variable believed to influence the dependent variable. • Self-Enhancing Cognitions • The tendency to report an overly positive self-view

  12. Stress Response Causes Self- Enhancement IV DV Hypotheses • Dependent Variable - The Effect. The variable believed to be influenced by the independent variable. • Physiological Stress Response

  13. Quick Quiz:Independent vs. Dependent Variables • A cognitive psychologist finds an association between alcohol consumption (0 drinks, 2 drinks, 5 drinks) and reaction time during a driving simulation task. • A clinical psychologist develops an experiment to test the type of therapy that is most effective in the treatment of test anxiety among male college students. • An organizational psychologist examines whether job performance is related to the number of breaks allowed during an 8-hour shift. • A social psychologist finds an association between marital satisfaction and overtime-hours worked.

  14. How Does Self-Enhancement Affect Stress Response? • “Mediators” or “Mechanisms” • Psychological • Distress • Health • Resources Physiological Stress Response Self-Enhancement

  15. Defining Variables • Conceptual Definition • Definition at the theoretical level • Similar to a dictionary definition • Only one conceptual definition

  16. Defining Variables • Operational Definition • The procedures used to measure or manipulate the variable • Countless operational definitions are possible Stress Response Conceptual Level Direct Self-Report Cardiovascular Reactivity Neuro- endocrine Observation Operational Level

  17. Measurement • Assignment of numbers to specific observations to reflect their variation • Scales of Measurement • Nominal/Categorical • Ordinal • Interval • Ratio

  18. How was the independent variable operationalized? • Self-Enhancement • How I See Myself Questionnaire • 21 Positive Qualities (academic ability, self-respect) • 21 Negative Qualities (selfish, pretentious) • Rate Self relative to Peers • Scale: • 1 (much less than average) • 7 (much more than average) • Self-Enhancement Score • Negative items were reverse scored • 42 ratings were averaged • Possible range 1 to 7, with values above 4 indicating self-enhancement relative to peers

  19. How was the dependent variable operationalized? • Chronic Indicators • Baseline Cortisol from saliva samples • Baseline Heart Rate and Blood Pressure • Acute Response to Stress • Changes in cortisol, HR, and BP • Counting backward task • While videotaped • Diagnostic of mental ability • Your score will be compared to others’ scores • Go faster!

  20. How were the potential mediators operationalized? • Psychological distress, health, and resources • all standard self-report measures

  21. Study Design • Was then Taylor et al. (2003) study a correlational study or a true experiment?

  22. Correlational Study • No manipulation of independent variable (self-enhancement) • Thus, no random assignment to conditions of the IV • IV = “predictor” variable • DV = “criterion” variable • Advantages and Disadvantages?

  23. Correlational Research • Advantages • Examine variables as they occur naturally • Examine relationships that might not be possible or ethical to manipulate • Gain converging evidence for the theory • in combo. with experimental research • Disadvantage • Cannot determine cause and effect • because no random assignment to levels of IV

  24. Correlation Does Not Equal Causation

  25. Aggression ? Stress Response ? Why a Correlation Does Not Imply “Cause and Effect” • Reverse Causality Problem Media Violence Self- Enhancement

  26. Genetic Predisposition Why a Correlation Does Not Imply “Cause and Effect” • Third Variable Problem Self- Enhancement Stress Response

  27. What is reliability? • Reliability = consistency of measurement • Observed Score = “True” Score + measurement error • The less measurement error, the greater the reliability • How minimize measurement error? • Use a Good Measure • Clear wording, limit response bias, etc. • Use a Good Procedure to Administer it • Train experimenters; Use standardized setting and instructions • Limit Mistakes in: • Participant responses • Data entry .00 (Scores are Random) to 1.00 (Perfect Reliability) Reliability Indexes Range from:

  28. Reliability • Random errors are self-canceling • Multiple measures improve reliability • aggregation • Aggregation also allows for calculating a reliability coefficient

  29. Reliability Coefficients • Split-Half, Test-Retest, and Equivalent Forms Reliability • Pearson correlation (r) • Internal Consistency • Spearman-Brown formula (R) • Kuder-Richardson formula 20 (K-R 20) • Cronbach’s alpha (α) • Interrater Reliability • Percent Agreement (can be misleading) • Cohen’s kappa (κ) • Intraclass r

  30. Cronbach’s Coefficient Alpha • Estimate of average r among all the items • Equivalent to the average of all possible split-half reliabilities

  31. σ21 = .962 σ22 = .797 σ23 = 1.126 Σ = 2.885

  32. Spearman-Brown Formula • Reliability coefficients increase as the number of items increases Word of caution

  33. Interrater Reliability • Kappa for Nominal Judgments Percent Agreement = (18 + 25 + 26)/100 = 69% Kappa “corrects” for chance agreement = .53

  34. Closer to Bull’s eye = Validity Consistency of Attempts = Reliability A = Neither Reliable nor Valid B = Reliable but not Valid C = Reliable and Valid

  35. Quick Quiz:Reliability and Validity • Which of the following is true: In order to be valid, a measure must also be reliable In order to be reliable, a measure must also be valid If you determine that a measure is reliable, that tells you that it is also valid

  36. Other Types of Validity • Internal and External Validity • More about these in a couple of weeks

  37. Practical Exercise • Dataset • 159 survey respondents • Fear of Negative Evaluation • 1 to 7 scale • Self-Enhancement • 10 enhancement items • 1 to 10 scale • Your Task • Test Reliability of Self-Enhancement Scale • Test for Correlation between Self-Enhancement and Fear of Negative Evaluation • Test for Gender Differences in Self-Enhancement and Fear of Negative Evaluation

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