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Research Methods in Psychology

Definitions of Variables

  • Variable: Anything that has at least 2 levels (i.e., it varies).

  • Psychological Construct: Abstract psychological variables thought of as concepts or topics (e.g., memory, aggression, anxiety).

Hypotheses

  • Statements about the relationship between variables/constructs.

  • Predictions derived from hypotheses.

Operational Definitions

  • Definition of variables based on how they are measured or manipulated.

  • Essential for both independent and dependent variables.

Purpose of Operational Definitions

  1. Ensure consistency in measurement.

  2. Allow replication by other researchers.

  3. Measure and test variables in alternative ways for converging evidence.

  4. Determine appropriate statistical analyses depending on scale of measurement.

Scales of Measurement

  • Nominal: Categorical variables without numerical properties (e.g., male/female).

  • Ordinal: Rank-ordered categories; unequal units (e.g., education levels).

  • Interval: Equal measurements between numbers, no absolute zero (e.g., temperature).

  • Ratio: Absolute zero present; allows comparison of magnitudes (e.g., time, length).

Types of Variables

  • Continuous: Data on a continuum (e.g., age).

  • Discrete: Categorical data chunked (e.g., children/adults).

Types of Measures

  1. Self-Report Measures: Direct responses from participants (e.g., questionnaires).

    • Types: Behavioral, Cognitive, Affective.

    • Issues: Potential errors in self-reporting.

  2. Tests: Instruments measuring individual differences (e.g., personality tests).

  3. Behavioral Measures: Observations and recordings of behavior, direct or indirect.

    • Includes operational definitions for behaviors and potential observational errors.

  4. Physical Measures: Bodily activities measured with equipment (e.g., fMRI).

Operational Definition Examples for Psychological Constructs (e.g., Fear)

  • Scale: Choose between discrete (scared vs. not scared) and continuous (frequency of fear).

  • Type of Measure: Utilize self-report, tests, behavioral, or physical measures.

Final Points

  • Clarity in operational definitions enhances precision and understanding in research.

  • Ethical considerations are crucial in the research process (e.g., Milgram's study on obedience).