G Factor

g factor (psychometrics): Psychometric factor also known as "general intelligence"... The g factor typically accounts for 40 to 50 percent of the between-individual performance differences on a given cognitive test, and composite scores ("IQ scores") based on many tests are frequently regarded as estimates of individuals' standing on the g factor.

g factor itself is a mathematical construct indicating the level of observed correlation between cognitive tasks. The measured value of this construct depends on the cognitive tasks that are used, and little is known about the underlying causes of the observed correlations.

Scientists consider g to be a statistical regularity and uncontroversial, and a general cognitive factor appears in data collected from people in nearly every human culture. Yet, there is no consensus as to what causes the positive correlations between tests.

Research in the field of behavioral genetics has shown that the construct of g is highly heritable in measured populations

Stephen J. Gould famously denounced the concept of g as supporting an unrealistic reified view of human intelligence

Full-scale IQ scores from a test battery will usually be highly correlated with g factor scores, and they are often regarded as estimates of g. For example, the correlations between g factor scores and full-scale IQ scores from David Wechsler's tests have been found to be greater than .95.

Tests that have the same difficulty level, as indexed by the proportion of test items that are failed by test takers, may exhibit a wide range of g loadings. For example, tests of rote memory have been shown to have the same level of difficulty but considerably lower g loadings than many tests that involve reasoning.

Practical validity

Some researchers have argued that it is more far-ranging and universal than any other known psychological variable

Others have argued that tests of specific abilities outperform g factor in analyses fitted to certain real-world situations.

The predictive validity of g is most conspicuous in the domain of scholastic performance

In elementary school, the correlation between IQ and grades and achievement scores is between .60 and .70. At more advanced educational levels, more students from the lower end of the IQ distribution drop out, which restricts the range of IQs and results in lower validity coefficients

Research suggests that the SAT, widely used in college admissions, is primarily a measure of g. A correlation of .82 has been found between g scores computed from an IQ test battery and SAT scores.

Research indicates that tests of g are the best single predictors of job performance, with an average validity coefficient of .55

The correlation between income and g, as measured by IQ scores, averages about .40 across studies.

Many social behavior problems, such as dropping out of school, chronic welfare dependency, accident proneness, and crime, are negatively correlated with g independent of social class of origin.

Genetic and environmental determinants

Relation to other psychological constructs

Elementary cognitive tasks

Working memory

Piagetian tasks (Jean Piaget)

It has been shown that it is possible to construct a battery consisting of Piagetian tasks that is as good a measure of g as standard IQ tests.

Personality

In a 2007 meta-analysis the correlations between g and the "Big Five" personality traits were found to be as follows:
conscientiousness −.04
agreeableness .00
extraversion .02
openness .22
emotional stability .09

The same meta-analysis found a correlation of .20 between self-efficacy and g.

Creativity

Criticism

Relation with Eugenics and Racialism

Gf-Gc theory - Main article: Fluid and crystallized intelligence

Theories of uncorrelated abilities

Flynn's model

The Mismeasure of Man

Critique of Gould

Other critiques of g