mteb/BrightProPsychologyRetrieval huggingface dataset:
Parametric statistical tests
 typically
assume that samples come from normally distributed populations, but the
central limit theorem means that this assumption isn’t necessary to meet when
you have a large enough sample.
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Cattell–Horn–Carroll theory  

Main article:  Cattell–Horn–Carroll theory

 Psychologist  Raymond
Cattell  defined  fluid and
crystallized intelligence  and authored the  Cattell Culture Fair III
 IQ test.

 Raymond Cattell  (1941) proposed
two types of cognitive abilities in a revision of Spearman's concept of
general intelligence.  Fluid intelligence  (Gf) was hypothesized as the ability to solve novel problems by
using reasoning, and  crystallized intelligence
 (Gc) was
hypothesized as a knowledge-based ability that was very dependent on education
and experience. In addition, fluid intelligence was hypothesized to decline
with age, while crystallized intelligence was largely resistant to the effects
of aging. The theory was almost forgotten, but was revived by his student 
John L. Horn  (1966) who later argued Gf
and Gc were only two among several factors, and who eventually identified nine
or ten broad abilities. The theory continued to be called Gf-Gc theory.  [30]
Other accomplishments  

Average adult combined IQs associated with real-life accomplishments by
various tests:  [180]  [181]  Accomplishment  |  IQ  |  Test/study  |  Year
---|---|---|---
MDs, JDs, and PhDs  |  125  |   WAIS-R  |  1987
College graduates  |  112  |   KAIT  |  2000
 K-BIT  |  1992
115  |  WAIS-R  |
1–3 years of college  |  104  |  KAIT  |
K-BIT  |
105–110  |  WAIS-R  |
Clerical and sales workers  |  100–105  |  |
High school graduates, skilled workers (e.g., electricians, cabinetmakers)  |
100  |  KAIT  |
WAIS-R  |
97  |  K-BIT  |
1–3 years of high school (completed 9–11 years of school)  |  94  |  KAIT  |
90  |  K-BIT  |
95  |  WAIS-R  |
Semi-skilled workers (e.g. truck drivers, factory workers)  |  90–95  |  |
Elementary school graduates (completed eighth grade)  |  90  |  |
Elementary school dropouts (completed 0–7 years of school)  |  80–85  |  |
Have 50/50 chance of reaching high school  |  75  |  |
Average IQ of various occupational groups:  [182]  Accomplishment  |  IQ  |
Test/study  |  Year
---|---|---|---
2023.11.08
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Health  

Main articles:  Impact of health on intelligence

and  Cognitive epidemiology 

Health is important in understanding differences in IQ test scores and other
measures of cognitive ability. Several factors can lead to significant
cognitive impairment, particularly if they occur during pregnancy and
childhood when the brain is growing and the blood–brain barrier is less
effective. Such impairment may sometimes be permanent, or sometimes be
partially or wholly compensated for by later growth.  [148]

Since about 2010, researchers such as Eppig, Hassel, and MacKenzie have found
a very close and consistent link between IQ scores and infectious diseases,
especially in the infant and preschool populations and the mothers of these
children.  [149]  They have postulated that fighting infectious diseases
strains the child's metabolism and prevents full brain development. Hassel
postulated that it is by far the most important factor in determining
population IQ. However, they also found that subsequent factors such as good
nutrition and regular quality schooling can offset early negative effects to
some extent.

Developed nations have implemented several health policies regarding nutrients
and toxins known to influence cognitive function. These include laws requiring
fortification of certain food products  [150]  and laws establishing safe
levels of pollutants (e.g.  lead  , [ mercury
) [
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Other theories  

An alternative to standard IQ tests, meant to test the  proximal development
 of
children, originated in the writings of psychologist  Lev Vygotsky
 (1896–1934) during his last two years of
his life.  [57]  [58]  According to Vygotsky, the maximum level of complexity
and difficulty of problems that a child is capable to solve under some
guidance indicates their level of potential development. The difference
between this level of potential and the lower level of unassisted performance
indicates the child's zone of proximal development.  [59]  Combination of the
two indexes—the level of actual and the zone of the proximal
development—according to Vygotsky, provides a significantly more informative
indicator of psychological development than the assessment of the level of
actual development alone.  [60]  [61]  His ideas on the zone of development
were later developed in a number of psychological and educational theories and
practices, most notably under the banner of  dynamic assessment
 , which seeks to measure
developmental potential  [62]  [63]  [64]  (for instance, in the work of 
Reuven Feuerstein  and his
associates,  [65]  who has [ criticized standard IQ testing
](/wiki/Reuven_Feuerstein
General factor ( _g_ )  ") ]

Main article:  _g_ factor  "G factor
\(psychometrics\)")

The many different kinds of IQ tests include a wide variety of item content.
Some test items are visual, while many are verbal. Test items vary from being
based on abstract-reasoning problems to concentrating on arithmetic,
vocabulary, or general knowledge.

The British psychologist  Charles Spearman  in 1904 made the first formal  factor analysis
 of  correlations
 between the tests. He observed that
children's school grades across seemingly unrelated school subjects were
positively correlated, and reasoned that these correlations reflected the
influence of an underlying general mental ability that entered into
performance on all kinds of mental tests. He suggested that all mental
performance could be conceptualized in terms of a single general ability
factor and a large number of narrow task-specific ability factors. Spearman
named it _g_ for "general factor" and labeled the specific factors or
abilities for specific tasks _s_ .  [35]  In any collection of test items that
make up an IQ test, the score that best measures _g_ is the composite score
that has the highest correlations with all the item scores. Typically, the "
_g_ -loaded" composite score of an IQ test battery appears to involve a common
strength in abstract reasoning across the test's item content.  [ _ citation
needed   _ ]
In a probability density function, the area under the curve tells you
probability. The normal distribution is a  **probability distribution**
 , so the
total area under the curve is always 1 or 100%.
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Shared family environment  

Family members have aspects of environments in common (for example,
characteristics of the home). This shared family environment accounts for
0.25–0.35 of the variation in IQ in childhood. By late adolescence, it is
quite low (zero in some studies). The effect for several other psychological
traits is similar. These studies have not looked at the effects of extreme
environments, such as in abusive families.  [15]  [120]  [121]  [122]
Each _z_ -score is associated with a probability, or  _p_ -value
 , that tells you the likelihood
of values below that _z_ -score occurring. If you convert an individual value
into a _z_ -score, you can then find the probability of all values up to that
value occurring in a normal distribution.
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There are both visual and formal statistical tests that can help you check if
your model residuals meet the assumption of normality. In  Prism
 , most models (ANOVA,
Linear Regression, etc.) include tests and plots for evaluating normality, and
you can also  test a column of data directly

.
Reliability and validity
Guilford's_Structure_of_Intellect "J.P.
Guilford") (1967) model of intelligence used three dimensions, which, when
combined, yielded a total of 120 types of intelligence. It was popular in the
1970s and early 1980s, but faded owing to both practical problems and 
theoretical  criticisms.  [30]

 Alexander Luria  's earlier work
on neuropsychological processes led to the PASS theory (1997). It argued that
only looking at one general factor was inadequate for researchers and
clinicians who worked with learning disabilities, attention disorders,
intellectual disability, and interventions for such disabilities. The PASS
model covers four kinds of processes (planning process, attention/arousal
process, simultaneous processing, and successive processing). The planning
processes involve decision making, problem solving, and performing activities
and require goal setting and self-monitoring.

The attention/arousal process involves selectively attending to a particular
stimulus, ignoring distractions, and maintaining vigilance. Simultaneous
processing involves the integration of stimuli into a group and requires the
observation of relationships. Successive processing involves the integration
of stimuli into serial order. The planning and attention/arousal components
comes from structures located in the frontal lobe, and the simultaneous and
successive processes come from structures located in the posterior region of
the cortex.  [68]  [69]  [70]  It has influenced some recent IQ tests, and
been seen as a complement to the Cattell–Horn–Carroll theory described above.
[30]
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In a normal distribution, data is symmetrically distributed with no  skew
 . When plotted on a graph, the
data follows a bell shape, with most values clustering around a  central
region  and tapering
off as they go further away from the center.
saw as the remarkable diversity of intelligence and the subsequent need to
study it using qualitative, as opposed to quantitative, measures (White,
2000). American psychologist  Henry H. Goddard  published a translation of it in 1910. American
psychologist  Lewis Terman  at  Stanford
University  revised the
Binet–Simon scale, which resulted in the  Stanford–Binet Intelligence Scales
 (1916). It became the most popular test in the United
States for decades.  [30]  [32]  [33]  [34]
###  Comment
Figure 2. Normal (left) vs. non-normal distribution. The red curve represents
an ideal normal (Gaussian) distribution.
You may also visually check normality by plotting a  frequency distribution

, also called a histogram, of the data and visually comparing it to a normal
distribution (overlaid in red). In a frequency distribution, each data point
is put into a discrete bin, for example (-10,-5], (-5, 0], (0, 5], etc. The
plot shows the proportion of data points in each bin.
####  Q-Q Plot
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The  measures of central tendency
 (mean, mode, and
median) are exactly the same in a normal distribution.
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Understanding the properties of normal distributions means you can use 
inferential statistics  to compare different groups and make estimates about populations
using samples.
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* Normality Test Explained: Methods Of Assessing Normality
Gene-environment interaction  

 David Rowe  reported an interaction of
genetic effects with  socioeconomic status  , such that the heritability was high in high-SES
families, but much lower in low-SES families.  [129]  In the US, this has been
replicated in infants,  [130]  children,  [131]  adolescents,  [132]  and
adults.  [133]  Outside the US, studies show no link between heritability and
SES.  [134]  Some effects may even reverse sign outside the US.  [134]  [135]

Dickens and Flynn (2001) have argued that genes for high IQ initiate an
environment-shaping  feedback cycle  , with
genetic effects causing bright children to seek out more stimulating
environments that then further increase their IQ. In Dickens' model,
environment effects are modeled as decaying over time. In this model, the
Flynn effect can be explained by an increase in environmental stimulation
independent of it being sought out by individuals. The authors suggest that
programs aiming to increase IQ would be most likely to produce long-term IQ
gains if they enduringly raised children's drive to seek out cognitively
demanding experiences.  [136]  [137]
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2023.09.07
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Models and theories  |

*  Cattell–Horn–Carroll theory 
*  Fluid and crystallized intelligence 
*  Multiple-intelligences theory 
*  PASS theory 
*  Three-stratum theory 
*  Triarchic theory 

Areas of research  |

*  Evolution of human intelligence 
*  Heritability of IQ 
*  Psychometrics 
*  Intelligence and environment  /  fertility  /  height  /  health  /  longevity  /  neuroscience  /  personality  /  race  /  sex 

*   Outline of human intelligence  /  thought
Classification  

Main article:  IQ classification 

Physicist  Stephen Hawking  . When
asked his IQ, he replied: "I have no idea. People who boast about their IQ are
losers."  [216]

IQ classification is the practice used by IQ test publishers for designating
IQ score ranges into various categories with labels such as "superior" or
"average".  [181]  IQ classification was preceded historically by attempts to
classify human beings by general ability based on other forms of behavioral
observation. Those other forms of behavioral observation are still important
for validating classifications based on IQ tests.
Keywords: normal distribution
Authority control databases  : National  [ 
](https://www.wikidata.org/wiki/Q170277
2023.09.01
The empirical rule, or the 68-95-99.7 rule, tells you where most of the values
lie in a  normal distribution  :
What is a t-distribution?
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Difference_between_IQ_test_and_Dynamic_Assessment
"Reuven Feuerstein") for its putative assumption or acceptance of "fixed and
immutable" characteristics of intelligence or cognitive functioning). Dynamic
assessment has been further elaborated in the work of  Ann Brown
 , and  John D. Bransford
 and in theories of  multiple
intelligences 
authored by  Howard Gardner  and 
Robert Sternberg  .  [66]  [67]

 J.P. Guilford  's [ Structure of
Intellect ](/wiki/J.P._Guilford
* The  mean  ,  median  and  mode  are exactly the same.
* The distribution is symmetric about the mean—half the values fall below the mean and half above the mean.
* The distribution can be described by two values: the mean and the  standard deviation  .
The _t_ -distribution forms a bell curve when plotted on a graph. It can be
described mathematically using the mean and the  standard deviation
 .
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plus exam") which incorporated an intelligence test has been used from 1945 to
decide, at eleven years of age, which type of school a child should go to.
They have been much less used since the widespread introduction of 
comprehensive schools  .
Formula  |  Calculation
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The most common graphical tool for assessing normality is the  Q-Q plot
 . In these plots, the observed data is plotted
against the  expected quantiles of a normal distribution
 . It
takes practice to read these plots. In theory, sampled data from a normal
distribution would fall along the dotted line. In reality, even data sampled
from a normal distribution, such as the example QQ plot below, can exhibit
some deviation from the line.
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What is the empirical rule?
Current tests  

 Normalized IQ
distribution with mean 100 and standard deviation 15

There are a variety of individually administered IQ tests in use in the
English-speaking world.  [71]  [72]  [73]  The most commonly used individual
IQ test series is the  Wechsler Adult Intelligence Scale (WAIS)

for adults and the  Wechsler Intelligence Scale for Children
 (WISC) for school-age test-takers. Other commonly used
individual IQ tests (some of which do not label their standard scores as "IQ"
scores) include the current versions of the  Stanford–Binet Intelligence
Scales  ,  Woodcock–Johnson Tests of Cognitive Abilities
 , the  Kaufman Assessment
Battery for Children  , the  Cognitive Assessment System
 , and the 
Differential Ability Scales  .

There are various other IQ tests, including:
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School performance  

The  American Psychological Association
 's report _Intelligence: Knowns and Unknowns_ states that
wherever it has been studied, children with high scores on tests of
intelligence tend to learn more of what is taught in school than their lower-
scoring peers. The correlation between IQ scores and grades is about .50. This
means that the explained variance is 25%. Achieving good grades depends on
many factors other than IQ, such as "persistence, interest in school, and
willingness to study" (p. 81).  [15]

It has been found that the correlation of IQ scores with school performance
depends on the IQ measurement used. For undergraduate students, the Verbal IQ
as measured by WAIS-R has been found to correlate significantly (0.53) with
the grade point average (GPA) of the last 60 hours (credits). In contrast,
Performance IQ correlation with the same GPA was only 0.22 in the same study.
[152]

Some measures of educational aptitude correlate highly with IQ tests – for
instance,  Frey & Detterman (2004)  reported a correlation of 0.82 between _g_
(  general intelligence factor  ) and  SAT  scores;  [153]  another
research found a correlation of 0.81 between _g_ and  GCSE
 scores, with the explained variance ranging "from 58.6%
in Mathematics and 48% in English to 18.1% in Art and Design".  [154]
Published on October 23, 2020 by  Pritha Bhandari
 .
Revised on June 21, 2023.
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Health and mortality  

Multiple studies conducted in Scotland have found that higher IQs in early
life are associated with lower mortality and morbidity rates later in life.
[178]  [179]
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* Normally distributed data examples