Unit 5: Defining and Measuring Variables

Theoretical constructs

Concepts that cannot be directly observed but are used to explain and predict behaviours in research.

Operational Definitions

Specific explanations of abstract concepts that translate them into measurable variables.

Conceptual Definition

A statement that outlines the theoretical meaning of a concept, providing a broader context for understanding a variable in research.

Operational Definition

A clear, precise description of how a variable will be measured or manipulated in research.

Diener’s 5-Item Subjective Well-Being Scale

A widely used measure that assesses individuals' subjective perceptions of their happiness and life satisfaction through five specific items.

Cantril’s Ladder of Life Scale

A tool used to measure subjective well-being, asking individuals to rate their current life satisfaction on a scale from 0 to 10, represented as a ladder.

Kahneman & Deaton (2010): Income and Happiness Study

A research study examining the relationship between income levels and reported happiness, concluding that higher income correlates with increased life satisfaction, but beyond a certain threshold, additional income does not significantly boost happiness.

Emotional Well-Being

Refers to the positive effects of emotions and moods on an individual's overall mental health and life satisfaction. It involves experiencing positive feelings, such as joy and contentment, and having a sense of fulfillment in life.

Life Evaluation

The cognitive assessment of one's life as a whole, often using tools like Cantril's Ladder to gauge overall life satisfaction through reflective judgment.

Reliability

The consistency of a measure over time and across different contexts, ensuring that the results are stable and can be replicated.

Test-Retest Reliability

Refers to the consistency of a measure across multiple administrations. It evaluates whether the same results can be obtained when a test is repeated over time.

Inter-Rater Reliability

The degree to which different raters or observers give consistent estimates of the same phenomenon. This type of reliability is crucial in ensuring that assessments are objective and reliable.

Internal Reliability

Refers to the consistency of results across items within a test. It assesses whether multiple measures that are intended to assess the same construct yield similar results.

Cronbach’s Alpha

A statistic used to measure the internal consistency or reliability of a set of items in a test. It ranges from 0 to 1, with higher values indicating greater reliability.

Validity

The extent to which a test measures what it claims to measure, reflecting the accuracy and relevance of the assessment in evaluating the intended construct.

Construct Validity

The degree to which a test accurately measures the theoretical construct it is intended to measure.

Face Validity

The extent to which a test appears to measure what it is supposed to measure, based on subjective judgment.

Content Validity

The extent to which a test represents all aspects of the construct it is intended to measure, ensuring that the content covers the entire domain relevant to the construct.

Criterion Validity

The extent to which a measure is related to an outcome. It assesses how well one measure predicts an outcome based on another measure.

Predictive Validity

A type of criterion validity that evaluates how well a test predicts future outcomes or behaviour. It determines the effectiveness of a measure in forecasting results based on another established outcome.

Concurrent Validity

A type of criterion validity that assesses the extent to which a measure correlates with an outcome measured at the same time. It determines the validity of a test by comparing it to a relevant criterion.

Known Groups Validity

A type of criterion validity that determines the extent to which a measure can distinguish between different groups known to differ on the outcome.

Convergent Validity

A type of validity that assesses the degree to which two measures that are supposed to be related actually correlate with one another. It indicates that a test is measuring the same construct as another test.

Discriminant (Divergent) Validity

A type of validity that evaluates the extent to which a measure does not correlate with measures of different constructs.

Self-Report Measures

Assessments where individuals provide their own responses regarding their thoughts, feelings, or behaviours, often through surveys or questionnaires.

Social Desirability Bias

A tendency for individuals to respond to self-report measures in a manner that they believe will be viewed favourably by others, potentially distorting their true thoughts and feelings.

Physiological Measures

Assessments that use biological indicators, such as heart rate or brain activity, to evaluate psychological states or reactions.

Polygraph (lie detector) Test

A physiological measure that assesses deception by recording physiological responses such as heart rate, blood pressure, and respiratory rate while a subject answers questions. It is based on the premise that deceptive answers will produce physiological changes that can be measured.

Observational (Behavioural) Measures

Methods used to assess behaviour by observing individuals in natural or controlled settings, recording their actions without direct interaction.

Frequency

Refers to the number of occurrences of a particular event or behaviour within a specified time frame. In psychology, it is often used to quantify responses in observational or experimental research.

Latency

The time delay between a stimulus and an individual's response, often measured in seconds or milliseconds. Can indicate how quickly someone reacts to a stimulus.

Number of Errors

The total count of mistakes made by an individual during a task or assessment, often used as a performance metric in experimental research.

Multiple Measurement Modalities

The use of various methods to assess or collect data on a particular variable, which can enhance the reliability and validity of research findings.

Donald T. Campbell’s Principle

A concept stating that the more a variable is measured in different ways, the more accurate the assessment of that variable will be, thus enhancing the quality of research.