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.  

Additional functions are added sporadically.

History:

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.