Editing Factor analysis (section)

===History===
[[Charles Spearman]] was the first psychologist to discuss common factor analysis<ref name=":0">{{Cite book|last=Mulaik|first=Stanley A|title=Foundations of Factor Analysis. Second Edition|publisher=CRC Press|year=2010|isbn=978-1-4200-9961-4|location=Boca Raton, Florida|pages=6}}</ref> and did so in his 1904 paper.<ref>{{Cite journal|last=Spearman|first=Charles|date=1904|title=General intelligence objectively determined and measured|journal=American Journal of Psychology|volume=15|issue=2|pages=201–293|doi=10.2307/1412107|jstor=1412107}}</ref> It provided few details about his methods and was concerned with single-factor models.<ref>{{Cite journal|last=Bartholomew|first=D. J.|date=1995|title=Spearman and the origin and development of factor analysis|journal=British Journal of Mathematical and Statistical Psychology|volume=48|issue=2|pages=211–220|doi=10.1111/j.2044-8317.1995.tb01060.x}}</ref> He discovered that school children's scores on a wide variety of seemingly unrelated subjects were positively correlated, which led him to postulate that a single general mental ability, or ''[[G factor (psychometrics)|g]]'', underlies and shapes human cognitive performance.

The initial development of common factor analysis with multiple factors was given by [[Louis Leon Thurstone|Louis Thurstone]] in two papers in the early 1930s,<ref>{{Cite journal|last=Thurstone|first=Louis|date=1931|title=Multiple factor analysis|journal=Psychological Review|volume=38|issue=5|pages=406–427|doi=10.1037/h0069792}}</ref><ref>{{Cite journal|last=Thurstone|first=Louis|date=1934|title=The Vectors of Mind|journal=The Psychological Review|volume=41|pages=1–32|doi=10.1037/h0075959}}</ref> summarized in his 1935 book, ''[[The Vectors of Mind|The Vector of Mind]].''<ref>{{Cite book|last=Thurstone|first=L. L.|title=The Vectors of Mind. Multiple-Factor Analysis for the Isolation of Primary Traits.|publisher=University of Chicago Press|year=1935|location=Chicago, Illinois}}</ref> Thurstone introduced several important factor analysis concepts, including communality, uniqueness, and rotation.<ref>{{Cite book|last=Bock|first=Robert|title=Factor Analysis at 100|publisher=Lawrence Erlbaum Associates|year=2007|isbn=978-0-8058-6212-6 |editor=Cudeck, Robert |editor2=MacCallum, Robert C.|location=Mahwah, New Jersey|pages=37|chapter=Rethinking Thurstone}}</ref> He advocated for "simple structure", and developed methods of rotation that could be used as a way to achieve such structure.<ref name=":0" />

In [[Q methodology]], [[William Stephenson (psychologist)|William Stephenson]], a student of Spearman, distinguish between ''R'' factor analysis, oriented toward the study of inter-individual differences, and ''Q'' factor analysis oriented toward subjective intra-individual differences.<ref>{{cite book | author= Mckeown, Bruce | title= Q Methodology | isbn= 9781452242194 | oclc= 841672556| date= 2013-06-21 | publisher= SAGE Publications }}</ref><ref>{{cite journal |title=Technique of Factor Analysis |journal=Nature |last=Stephenson |first=W. |volume=136 |issue=3434 |page=297 |date=August 1935 |issn=0028-0836 |doi=10.1038/136297b0|bibcode=1935Natur.136..297S |s2cid=26952603 |doi-access=free }}</ref>

[[Raymond Cattell]] was a strong advocate of factor analysis and [[psychometrics]] and used Thurstone's multi-factor theory to explain intelligence. Cattell also developed the [[Scree plot|scree test]] and similarity coefficients.