Software and data sets to do classic and modern psychometrics, and to analyze personality  and experimental psychological data sets. 

The psych package has been developed as a supplement to courses in research methods in psychology, personality research, and graduate level psychometric theory.

The functions are a supplement to the text (in progress): An introduction to psychometric theory with applications in R. 

Additional functions are added sporadically.

History:


January 2009: 1-0.63

Added structure.graph and structure.sem to create graphical output and pre-sem commands for sem.
Modified omega.graph to return sem commands for running the sem function from John Fox.

Added Promax to report factor intercorrelations for promax rotations.

bug fix in VSS and omega to allow for promax rotations.

correction to winsor so that it does not sort the vectors of the input data.frame.

bug fix in principal (for problem of oblique rotations)

continued improvements in the print.psych and summary.psych functions 
cleaned up sim.congeneric to reduce the amount of output (now handled through print.psych)

added super.matrix function (to combine two matrices -- useful for constructing keys and for doing examples in structure.graph)
Improvements to structure graph.

December 2008: 1-0.62
added the structure.graph function
added circadian functions 
renamed some functions to make the index order easier to follow.

September 2008: 1-0.58

Introduced the guttman function to estimate the 6 Guttman (1945) estimates (as well as a few others).

August 2008: 1.-0.54

Added print.psych and summary.psych generic functions to clean up the output of many of the functions. 


October-November, 2007

Introduced several new functions:

headtail   (combines head and tail functions to produce the first N and last M rows of a matrix or dataframe)

error.bars and 
error.bars.by     plot means with error bars by a grouping variable

omega       revised to allow for negatively keyed items.  Detects items that should be reversed.

June-September, 2007

score.multiple.choice   provides scores and item statistics for multiple choice items.

circ.sim              modified to be more general item simulations
circ.simulation
item.sim

polar                converts two dimensional factor loadings to polar coordinates.


