Research Methods in Psychology

Defining Variables in Research

• Variables are elements, characteristics, or factors that change and have at least two values.
• Variables can be easy to define, observe, and measure (e.g., room temperature: cold/warm, charity donation: yes/no).
• In the charity donation example, room temperature (cold, warm) is the manipulated variable, and donating (yes/no) is the measured variable.
• Researchers define and measure variables to examine relationships.

Constructs and Operational Definitions

• Many psychological phenomena are not directly observable (e.g., intelligence).
• Hypothetical constructs represent attributes, mechanisms, or processes presumed to exist but not directly measurable.
• These constructs manifest in observable phenomena.
• Operational definitions are essential for studying hypothetical constructs empirically.

Operational Definitions

• An operational definition describes a concept using observable and measurable procedures.
• Examples include: anxiety (test score, withdrawal, nervous system activation).
• Operational definitions clarify understanding and communication of variables to others.
• Operationalisation is creating an operational definition.
• Refining operational definitions involves reviewing previous research's definitions and methods—seeking areas for improvement.
• Multiple operational definitions might be necessary for complex constructs (e.g., intelligence, multiple aspects of intelligence).
• An operational definition translates abstract concepts into concrete terms.

Validity and Reliability

• Validity ensures a measurement procedure accurately measures the intended variable.
• Reliability confirms consistent results from repeated measurements of the same variable.
• A measure may be reliable without being valid.
• Using a ruler to measure height is a valid measure of height, whereas weighing someone is an invalid measurement of height.
• Validity is not an inherent property of the measure, depending on how it's used/applied. Measuring intelligence with an IQ test relies on understanding the language of the test and relevance to the culture of those tested.
• Evaluating validity involves considering whether a measure is measuring what it is designed to measure. A measurement might appear valid, but may not if there is no consideration given to factors that might influence the results, such as someone's anxiety interfering with a heart-rate measurement (or other confounding factors).
• Various types of validity exist to assess the accuracy of how something impacts how a variable is measured.