traits and measurement

Psychometrics

The field of psychology and statistics concerned with the theory and application of measuring latent psychological constructs.

Psychological Testing

The use of standardised instruments to measure hidden psychological attributes such as personality, intelligence, and mental health.

Purpose and Importance of Psychological Testing

Allows indirect assessment of hidden mental attributes and supports decision-making in education, employment, and clinical settings.

Psychological Measurement

The process of assigning numbers to human attributes so that psychological properties are represented quantitatively and meaningfully according to defined rules.

Operationalisation

Translating an abstract construct into measurable and observable indicators or test items.

Latent Psychological Construct

A hidden or unobservable attribute inferred from patterns of behaviour or responses.

Sampling

Selecting a subset of a population in order to estimate characteristics of the whole population.

Sample Representativeness

How accurately a selected group reflects the characteristics of the target population.

Importance of Representativeness

If the group used is biased, the results and norms can overestimate or underestimate true population values.

Psychological Test Scoring

Converting raw responses into a numerical value representing a psychological attribute.

Objective Scoring

Using fixed, standardised rules with minimal human judgement.

Subjective Scoring

Using expert judgement or interpretation when scoring responses.

Interpreting Test Results

Evaluating whether scores fairly reflect a person's attributes while considering bias, context, and limitations.

Standardisation

Transforming raw scores into standardised values using population norms.

Normative Scores

Values that allow comparison of an individual's performance relative to a reference population.

Standardisation Methods

Statistical methods used to transform raw scores, such as z-scores, T-scores, and percentile ranks.

Reification

The process of treating abstract concepts (like introversion or anxiety) as if they are real, tangible things.

Validity

The degree to which a test measures what it claims to measure.

Biases in Testing

Systematic errors that affect the results of psychological assessments, such as cultural biases or procedural biases.

Labeling

The process of categorizing individuals based on their test scores or observed behaviors, which can lead to stigmatization or misinterpretation.

Standardization

A method to ensure consistency in testing procedures and scoring to reduce variability and improve comparability.

Transformations

Converting scores from one metric to another (e.g., height in centimeters to inches) for better interpretation.

Z-score

A statistical measure that describes a score's relation to the mean in a group, expressed in standard deviation units.

Normative Data

Statistical data derived from a representative sample that allows comparison of an individual's score to a larger population.

Construct Validity

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

Convergent Validity

The degree to which a test correlates with other measures of the same construct.

Divergent Validity

The degree to which a test does not correlate with measures of different constructs.

Criterion Validity

The extent to which a measure correlates with an outcome (criterion), which can be concurrent or predictive.

Face Validity

The degree to which a test appears to measure what it claims to measure, based on subjective judgment.

Content Validity

The extent to which a test represents the entire domain of the construct it is intended to measure.

Ceiling Effect

A situation in which scores on a test are clustered at the high end, limiting differentiation.

Floor Effect

A situation where scores on a test are clustered at the low end, making it difficult to distinguish between lower scores.

Psychometric Validity

A specific type of validity that refers to the effectiveness of a psychological test in measuring its intended construct.

Sampling

The process of selecting a representative group from a population to estimate characteristics of the whole population.

Subjective Tests

Assessments that rely on personal interpretation, such as projective tests, which can introduce biases.

Role of Correlation in Validity

Correlation is used to evaluate validity by assessing the relationship between a test and other measures. For example, high positive correlations with similar measures indicate convergent validity, while low correlations with dissimilar measures suggest divergent validity, and correlations with outcomes indicate criterion validity.

Internal Validity

The extent to which a study establishes a cause-and-effect relationship between the independent and dependent variables, free from confounding factors.

External Validity

The extent to which the findings of a study can be generalized to other populations, settings, and times.

Ecological Validity

The degree to which the methods, materials, and settings of a study approximate the real-life situation that is being studied.

Operationalisation

The process of defining abstract concepts into measurable, observable variables for empirical research.

Reliability

The degree of stability across time or context in measurements.

Internal Consistency

The degree of consistency among items in a test or questionnaire.

Cronbach's Alpha

A coefficient that measures internal consistency between items in a test. Want between 0.6-0.8.

Test-Retest Reliability

The reliability of a test measured by the consistency of scores over time.

Inter-rater Reliability

The degree of agreement between two or more independent observers measuring the same phenomenon.

Observed Score

The score obtained from a psychological test or instrument. (X)

True Score

The actual score reflecting the true level of the psychological construct. (T)

Error Variance

The portion of the observed variance that is due to measurement error. (E)

Latent Variable

A variable that is not directly observed but is inferred from other observed variables. (X = T  + E)

Nomological Network

A theoretical framework that maps relationships between constructs.

Standard Error of Measurement

The standard deviation of observed scores from the true score, indicating the amount of error in measurement.

What is the fundamental equation of Classical Test Theory (CTT) relating observed scores, true scores, and error?

X = T + E
Where X is the observed score, T is the true score, and E is the error.

What does a higher reliability coefficient (e.g., Cronbach's alpha) indicate in psychological testing?

A higher reliability coefficient indicates that the test is more consistent and measures the construct with less random error, meaning observed scores are closer to true scores.

What is the typical range for reliability coefficients, and what is generally considered an acceptable level?

Reliability coefficients typically range from 0 to 1. A coefficient of .70 or higher is often considered acceptable for psychological research, while .90 and above is desirable for high-stakes decisions.

What are some strengths of Classical Test Theory (CTT)?

1. Simple and intuitive framework for understanding measurement error.

2. Widely used and forms the basis for many psychometric concepts.

3. Useful for developing and evaluating psychological tests.

What are some limitations of Classical Test Theory (CTT)?

1. Difficulty in separating person abilities from item characteristics (e.g., item difficulty).

2. Parameter estimates (e.g., item difficulty, person ability) are sample-dependent.

3. Assumes that the standard error of measurement is the same for all test-takers, which may not always be true.

4. Provides test-level information rather than information about specific items.

Reliability

The consistency of a measure; the degree to which it produces stable and consistent results.

Factor Analysis

A statistical method used to identify underlying relationships between variables.

Correlation Matrix

A table showing correlation coefficients between variables.

Pearson Correlation

A measure of the linear correlation between two variables.

Latent Constructs

Variables that are not directly observed but are inferred from other variables.

Items (or Indicators)

Observed variables that represent a latent construct.

Simple Structure

A factor loading pattern where each item loads highly on one factor and low on others.

Exploratory Factor Analysis

A technique used to identify the underlying relationships between items without a prior hypothesis.

Confirmatory Factor Analysis

A statistical technique used to test whether a set of variables represent a specific number of factors.

Eigenvalue

A value indicating the amount of variance captured by a factor in factor analysis.

Scree Plot

A graphical representation used to determine the number of factors to retain in a factor analysis.

Orthogonal Rotation

A method of rotation in factor analysis that assumes factors are uncorrelated.

Oblique Rotation

A method of rotation in factor analysis that allows for correlated factors.

Manifest Variables

Directly observed variables, as opposed to latent variables.

Cross Loading

When an observed variable loads on more than one factor.

Factor Loading

A value that represents the correlation between an observed variable and a factor.

Factorability

The ability to derive meaningful factors from a set of variables.

Bartlett's Test of Sphericity

A statistical test to assess whether a correlation matrix is significantly different from an identity matrix.

What is Allport's definition of personality?

Personality is the dynamic organization within the individual of those psychophysical systems that determine his unique adjustments to his environment." Key elements include "dynamic organization," "psychophysical systems," "determine," "unique adjustments," and "environment."

What is the distinction between Allport's concepts of common and individual traits?

1. Common Traits: Shared by many people within a culture, allowing for comparisons between individuals. 2. Individual Traits (or Personal Dispositions): Unique to a person and describe their distinctive style of behavior; they are more fundamental to the individual than common traits.

What are Cardinal Traits?

Traits that are so dominant that they influence nearly all of a person's behavior; not everyone has a cardinal trait.

What are Central Traits?

Traits that are fundamental to an individual's personality and can be used to describe most of their behaviors, but do not dominate their personality.

What are Secondary Traits?

Traits that are less central to an individual's personality and may influence behavior in specific situations.

What is the Proprium according to Allport?

A term used by Allport to refer to the self or the ego, which develops through personal experiences and interactions with the environment. It represents the unifying core of personality.

What is Functional Autonomy in Allport's theory?

A concept that suggests motives may change over time and that adult behaviors can be seen as independent from their original (often childhood) motivations.

What is the difference between perseverative and propriate functional autonomy?

1. Perseverative Functional Autonomy: Refers to routine behaviors and habits that are maintained without any direct reward or connection to one's core self (e.g., habitually taking a certain route to work even when another route is faster). 2. Propriate Functional Autonomy: Refers to values, interests, and attitudes that are central to one's self (proprium) and are maintained because they express who one genuinely is, contributing to one's sense of purpose and identity.

What is the Nomothetic Approach in psychology?

An approach in psychology that seeks to establish general laws and principles applicable to all individuals, emphasizing averages over individual differences.

What is the Ideographic Approach in psychology?

An approach that focuses on the individual and seeks to understand the nuances and unique aspects of a person's personality.

Strength of Allport’s Theory 

Emphasises individuality and the uniqueness of personal experiences in personality development.

Limitations of Allport's theory

Difficult to scientifically test and limited in predicting future behaviour due to its focus on personal uniqueness.

Big Five Personality Traits

A widely accepted model proposing five main dimensions or traits that define human personality: openness, conscientiousness, extraversion, agreeableness, and neuroticism.

Trait Theory

A psychological approach and theoretical framework proposing that personality is made up of a set of relatively stable traits that can be measured, differ among individuals, and influence behavior.

Temperament

Early-appearing, biologically based individual differences in reaction patterns, often evident in early childhood, that are considered a precursor to more complex personality traits and are less influenced by the environment than later-developing personality traits.

Heritability

A measure, often expressed as a percentage, indicating the proportion of variance in a trait within a population that can be attributed to genetic differences.

Dimensional Structure of Personality

The idea that personality traits can be organized along various dimensions, indicating that individuals exhibit traits on a continuum.

Lexical Approach

A method of studying personality and personality assessment that posits the most significant traits are embedded in the language we use to describe human behavior, categorizing traits based on common descriptors.

Probabilistic System

A characteristic of trait theories indicating that personality traits influence behavior but do not determine it absolutely.

What are the core assumptions of trait theories of personality?

1. Traits are stable over time and across situations. 2. Traits are internal, causal properties that explain behavior. 3. Traits can be measured and quantified. 4. Individuals differ in the amount of each trait they possess, creating individual differences.

How do trait theories differ from other approaches to personality (e.g., psychodynamic, humanistic)?

Trait theories primarily focus on describing and predicting personality through stable characteristics, rather than explaining underlying unconscious conflicts (psychodynamic) or emphasizing personal growth and self-actualization (humanistic).

How do genetic factors contribute to personality trait development?

Genetic factors influence the basic predispositions for certain traits, often measured as heritability. This biological foundation contributes to temperament, which forms an early basis for later personality traits.

How do environmental factors contribute to personality trait development?

Environmental factors, such as family upbringing, cultural influences, peer interactions, and unique life experiences, interact with genetic predispositions to shape and modify the expression of personality traits throughout life.

Explain the interaction between genetic and environmental factors in personality development.

Personality traits emerge from a continuous interplay between inherited genetic predispositions and environmental influences. Genes can affect how individuals respond to environments, and environments can influence the expression of genes.

What are common methods used to measure personality traits?

1. Self-report questionnaires: Individuals rate themselves on a series of items. 2. Observer ratings: Friends, family, or trained observers rate the individual. 3. Behavioral observations: Direct observation of behavior in specific situations.

What is the primary purpose of measuring personality traits?

The primary purpose is to describe individual differences, predict future behavior (e.g., job performance, relationship satisfaction), diagnose psychological conditions, and contribute to self-understanding.