Personality Project

The psych and psychTools packages may be thought of as a "Swiss Army knife" for psychological research. Not the best tool for specific tasks, but useful for many tasks. Among the more than 500 functions, there are convenient ways of reading data from the clipboard, local or remote files; for finding and plotting descriptive statistics; multiple ways of finding and displaying correlations; for factor analysis, cluster analysis and principal components analysis; finding multiple estimates of reliability, both internal consistency and test retest; doing linear regression from correlation matrices; scale construction for single or multiple scales and much more.

psych has been developed at the Personality, Motivation and Cognition laboratory in the Department of Psychology at Northwestern University since 2005 to include functions most useful for personality, psychometric, and psychological research. The package is also meant to supplement a text on Psychometric Theory, a draft of which is available on line.

psych is written in R which is a very powerful open source system for statistical computation and graphics. R consists of a language plus a run-time environment with graphics, a debugger, access to certain system functions, and the ability to run programs stored in script files. Base R is a foundation upon which more than 19,750 "packages" have been built. It is the use of these packages that makes R such a powerful tool for research.

The development of the psych package was done in conjunction with the development of the Synthetic Aperture Personality Assessment (SAPA) project and is a core part of the International Cognitive Ability Resource (ICAR) project. The SAPA project includes a personality test that uses a massively missing at random strategy to measure dimensions of temperament, ability, and interests.

To start using the psych package, it is, of course, necessary to install R and the psych package. Then one should read the Introduction and overview for psychometrics vignettes about psych and work through those examples. In addition, vignettes have been written for basic scale construction, factor analysis, principal components analysis, and cluster analysis , finding the various reliability estimates of omega_h, alpha, and omega_t, as well as regression and mediation analysis from raw data as well as from correlation matrices. There are several short courses demonstrating R as used for psychology. These are large files. Alternatively, the R guide might provide a good start.

Reporting bugs in the psych package