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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 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 • Statistical Inference • T-tests, confidence intervals, power, and effect size • Bivariate Correlation • Bivariate Regression • Partial Correlation/Multiple Regression
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
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.
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?
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
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.
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
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
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
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
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.
How Does Self-Enhancement Affect Stress Response? • “Mediators” or “Mechanisms” • Psychological • Distress • Health • Resources Physiological Stress Response Self-Enhancement
Defining Variables • Conceptual Definition • Definition at the theoretical level • Similar to a dictionary definition • Only one conceptual definition
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
Measurement • Assignment of numbers to specific observations to reflect their variation • Scales of Measurement • Nominal/Categorical • Ordinal • Interval • Ratio
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
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!
How were the potential mediators operationalized? • Psychological distress, health, and resources • all standard self-report measures
Study Design • Was then Taylor et al. (2003) study a correlational study or a true experiment?
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?
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
Correlation Does Not Equal Causation
Aggression ? Stress Response ? Why a Correlation Does Not Imply “Cause and Effect” • Reverse Causality Problem Media Violence Self- Enhancement
Genetic Predisposition Why a Correlation Does Not Imply “Cause and Effect” • Third Variable Problem Self- Enhancement Stress Response
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:
Reliability • Random errors are self-canceling • Multiple measures improve reliability • aggregation • Aggregation also allows for calculating a reliability coefficient
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
Cronbach’s Coefficient Alpha • Estimate of average r among all the items • Equivalent to the average of all possible split-half reliabilities
σ21 = .962 σ22 = .797 σ23 = 1.126 Σ = 2.885
Spearman-Brown Formula • Reliability coefficients increase as the number of items increases Word of caution
Interrater Reliability • Kappa for Nominal Judgments Percent Agreement = (18 + 25 + 26)/100 = 69% Kappa “corrects” for chance agreement = .53
Closer to Bull’s eye = Validity Consistency of Attempts = Reliability A = Neither Reliable nor Valid B = Reliable but not Valid C = Reliable and Valid
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
Other Types of Validity • Internal and External Validity • More about these in a couple of weeks
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