How We Evaluate Psychological Measures: Reliability & Validity

Intelligence Objectives 1. Psychological testing (includes standardization, test norms, percentile score, reliability [e.g., test-retest], and vali...
Author: Harold Little
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Intelligence

Objectives 1.

Psychological testing (includes standardization, test norms, percentile score, reliability [e.g., test-retest], and validity [e.g., criterion-related, content, construct] (some in text only)

2.

History of intelligence testing (includes Galton, Binet, Terman, Wechsler, WAIS, Sternberg’s Triarchic Theory, Gardner)

3.

Assessing contribution of heredity vs. environment on intelligence (includes twin and adoption studies)

4.

The "general" vs. "specific" debate (includes examples or analogies for each)

5.

Components of Spearman's ("g factor") vs. Sternberg's explanation of intelligence vs. Gardner’s explanation

6.

Correlates of creativity with personality and mental health

How We Evaluate Psychological Measures: Reliability & Validity

Reliability Informal Definition:

Validity Informal Definition:

The consistency and stability of measurement

Extent to which a test measures what it is supposed to measure

Examples of the Formal Definitions – NOT for Test Use in PSY 1101

Reliability

“The extent of unsystematic variation in the quantitative description of an individual when that individual is measured a number of times.” (Ghiselli, Campbell, & Zedeck, 1981, p. 482)

Validity

“… refers to the appropriateness, meaningfulness, and usefulness of the specific inferences made from test scores. Test validation is the process of accumulating evidence to support such inferences.” Standards for Educational and Psychological Testing (1985) p.9

The Evolution of Intelligence Testing • Sir Francis Galton (1869) – Hereditary Genius

• Alfred Binet and Theodore Simon (1905) – Binet asked to develop test for use with French school children – Binet-Simon Intelligence Scale • Mental age

• Lewis Terman (1916) – Stanford-Binet Intelligence Scale • Intelligence Quotient (IQ) – MA/CA x 100

• David Wechsler (1955) – Wechsler Adult Intelligence Scale ( adapted from Thomson Higher Education, 2007, 2001)

Defining Intelligence

Wechsler’s Definition: “Global capacity to act purposefully, think rationally, and deal effectively with the environment.” Other psychologists are more likely to use “cognitive abilities” or “mental abilities” versus “intelligence.”

(adapted from Wadsworth/Thomson Learning, 2001)

Cognitive or Mental Abilities Tests

 Also called “paper-and-pencil” tests for most common way given to applicants

 May measure overall mental ability (”G”) or specific cognitive areas (verbal, quantitative, memory, reasoning; “facets”) reflecting debate over general versus specific intelligences

 Common examples include Wonderlic Personnel Test, Wechsler Adult Intelligence Scale, and MANY others

WARNING: Potential for adverse impact on members of protected classes

Multiple Aptitude Test Batteries

Ployhart, R. E., Schneider, B., & Schmitt, N. (2006). Staffing organizations: Contemporary practice and theory (3rd ed.; p. 409). Mahwah, NJ Lawrence Erlbaum.

Average Wonderlic Scores

Guion, R. M., & Highhouse, S. (2006). Essentials of personnel assessment and selection (p. 240). Mahwah, NJ Lawrence Erlbaum.

Sample questions like those found on tests of mechanical aptitude. (adapted from Wadsworth/Thomson Learning, 2001)

(The answers are A and the Driver.)

(adapted from Wadsworth/Thomson Learning, 2001)

See Fig. 8.14, p. 252

( adapted from Thomson Higher Education, 2007, 2001)

Group Tests

• WAIS is example of individually-administered test • In contrast, “Group Tests” are given to several people with less supervision; usually contain multiple-choice items – Army Alpha was first group intelligence test; developed to screen for admission to officer candidate school during World War I

(adapted from Wadsworth/Thomson Learning, 2001)

Cognitive Abilities Tests: Criterion-Related Validity Estimates

Validity for “Job Performance” Criterion* .53 .54 .27 .28 .37

Occupation Manager Clerical Sales clerk Vehicle operator Industrial

* “Corrected” values from meta-analyses

(Hunter, 1986)

Cognitive Ability, Job Complexity, & Job Performance

See p. 255

Normal Distribution and IQ Scores

See Fig. 8.15, p. 253

Heredity and Environment

• “Nature AND Nurture” - Intelligence is probably a combination of heredity (genetics) AND environment (upbringing)

• “Twins Studies” are used to look at relative contributions of each factor – Fraternal Twins: Conceived from two separate eggs – Identical Twins: Develop from single egg and have identical genes

(adapted from Wadsworth/Thomson Learning, 2001)

Figure 8.19 Studies of IQ similarity

Reaction Range: Heredity & Environment

See p. 260

Alternative Ways of Viewing Intelligence

• G-Factor: General ability factor; assumed to explain high correlations among various intellectual measures • Sternberg - Triarchic Theory of Intelligence

• Gardner - Multiple Intelligences: Argues there are several specialized types of intellectual ability

( adapted from Thomson Higher Education, 2007, 2001)

Spearman’s g. Spearman found that specific mental talents (S1, S2, S3, and so on) were highly intercorrelated. Thus, he concluded that all cognitive abilities share a common core, which he labeled g for general mental ability.

(adapted from Wadsworth/Thomson Learning, 2001)

Sternberg’s Triarchic Theory of Intelligence

Analytical – abstract reasoning, judgment, evaluation Creative – creativity, inventiveness, deal with new problems Practical – learn and deal with everyday problems See Fig. 8.23, p. 263

Gardner’s Theory of Multiple Intelligences Logical – Mathematical Linguistic Musical Spatial

Bodily-Kinesthetic Interpersonal Intrapersonal Naturalist See Table 8.4, p. 264

Creativity & Mental Illness?

( adapted from Thomson Higher Education, 2007, 2001)

See p. 267

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