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What is the relation between Raymond Cattell and Factor analysis?
In the 1920s, Raymond Cattell worked with Charles Spearman, who was developing the new statistical technique of factor analysis, in his effort to understand basic dimensions and structure of human abilities.
What is the purpose of the effort of factor analysis applied?
Raymond Cattell postulated that factor analysis could be applied to other areas beyond the domain of abilities.
How do Raymond Cattell and Charles Spearman come about with the factor analysis?
Raymond Cattell made many important innovative contributions to factor analytic methodology, including the Screen Test, as well as the Rotoplot program for attaining maximum simple structure solutions.

Question: What is the meaning of correlated variables?
Self-contained rewrite: What is the meaning of correlated coefficient?