Raymond Bernard Cattell (20 March 1905 - 2 February 1998) was a British and American psychologist, known for his psychometric research into intrapersonal psychological structure. His work also explored the basic dimensions of personality and temperament, the range of cognitive abilities, the dynamic dimensions of motivation and emotion, the clinical dimensions of abnormal personality, patterns of group syntality and social behavior, applications of personality research to psychotherapy and learning theory, predictors of creativity and achievement, and many multivariate research methods including the refinement of factor analytic methods for exploring and measuring these domains. Cattell authored, co-authored, or edited almost 60 scholarly books, more than 500 research articles, and over 30 standardized psychometric tests, questionnaires, and rating scales. According to a widely cited ranking, Cattell was the 16th most eminent, 7th most cited in the scientific journal literature, and among the most productive, but controversial psychologists of the 20th century.
Multivariate research
Rather than pursue a "univariate" research approach to psychology, studying the effect that a single variable (such as "dominance") might have on another variable (such as "decision-making"), Cattell pioneered the use of multivariate experimental psychology (the analysis of several variables simultaneously). He believed that behavioral dimensions were too complex and interactive to fully understand variables in isolation. The classical univariate approach required bringing the individual into an artificial laboratory situation and measuring the effect of one particular variable on another - also known as the "bivariate" approach, while the multivariate approach allowed psychologists to study the whole person and their unique combination of traits within a natural environmental context. Multivariate experimental research designs and multivariate statistical analyses allowed for the study of "real-life" situations (e.g., depression, divorce, loss) that could not be manipulated in an artificial laboratory environment.  Cattell applied multivariate research methods across several intrapersonal psychological domains: the trait constructs (both normal and abnormal) of personality, motivational or dynamic traits, emotional and mood states, as well as the diverse array of cognitive abilities. In each of these domains, he considered there must be a finite number of basic, unitary dimensions that could be identified empirically. He drew a comparison between these fundamental, underlying (source) traits and the basic dimensions of the physical world that were discovered and presented, for example, in the periodic table of chemical elements.  In 1960, Cattell organized and convened an international symposium to increase communication and cooperation among researchers who were using multivariate statistics to study human behavior. This resulted in the foundation of the Society of Multivariate Experimental Psychology (SMEP) and its flagship journal, Multivariate Behavioral Research. He brought many researchers from Europe, Asia, Africa, Australia, and South America to work in his lab at the University of Illinois. Many of his books involving multivariate experimental research were written in collaboration with notable colleagues.

Q: what is the multivariate research?
A: Rather than pursue a "univariate" research approach to psychology, studying the effect that a single variable (such as "dominance") might have on another variable (such as "decision-making"),

Q: what else can you tell me about it?
A: Cattell pioneered the use of multivariate experimental psychology (the analysis of several variables simultaneously).

Q: what was being used before the multivariate?
A: He believed that behavioral dimensions were too complex and interactive to fully understand variables in isolation.

Q: how did  the multivariate help?
A: The classical univariate approach required bringing the individual into an artificial laboratory situation and measuring the effect of one particular variable on another

Q: on another what?
A: also known as the "bivariate" approach,

Q: how is the mutlivariate research different?
A: the multivariate approach allowed psychologists to study the whole person and their unique combination of traits within a natural environmental context.

Q: has the multivariate reseache been applied?
A: Cattell applied multivariate research methods across several intrapersonal psychological domains:
what types of domains?
the trait constructs (both normal and abnormal) of personality, motivational or dynamic traits, emotional and mood states, as well as the diverse array of cognitive abilities.
the trait constructs (both normal and abnormal) of personality, motivational or dynamic traits, emotional and mood states, as well as the diverse array of cognitive abilities.