science of personality assessment has progressed at a dismally slow pace since
the first personality inventories were developed over 75 years ago. What is
usually taken to be the earliest personality instrument, Woodworth's Personal
Data Sheet (PDS), was published in 1917, and since that time thousands of other
instruments have been developed. Like the PDS, most of these have been of limited
bandwidth, typically providing measures of one, two, or at most three traits.
Virtually all of these narrow-bandwidth instruments are in the public
domain--the items and their scoring keys having been published in scientific
books, journal articles, or student theses or dissertations. The items are freely
used by other scientists, either in their original form or quite commonly in
some customized format.
On the other hand, most broad-bandwidth personality inventories (like the MMPI, CPI, 16PF, and NEO-PI) are proprietary instruments, whose items are copyrighted by the test authors. As a consequence, the instruments cannot be used freely by other scientists, who thus cannot contribute to their further development and refinement. Indeed, broad-bandwidth inventories are rarely revised. At most, after many decades of commercial use, some of the most dated items might be changed and/or new norms established. For many inventories, nothing is ever done at all.
The manuals for some of these commercial inventories include tables of correlations between the scale scores and various criterion indices. But, such empirical findings are rarely used to actually influence scale development, much less to improve the quality of the scales. Even worse, virtually all of the findings from different inventories are incommensurate. Test authors are not encouraged to conduct comparative validity studies, pitting their instrument against one or more others as predictors of the same set of criterion indices. As a result, neither the science of personality assessment nor its applied practitioners have any information about the comparative performance of the different instruments available in the marketplace. There is no Consumers Union for testing our tests.
This IPIP website is intended as an international effort to develop and continually refine a set of personality inventories, whose items are in the public domain, and whose scales can be used for both scientific and commercial purposes. No one investigator alone has access to many diverse criterion settings, but the international scientific community has such access. By pooling our findings, we should be able to devise instruments over the next decade that make our present ones seem like ancient relics.
To get there, we need to start somewhere. To begin, we must agree on the solutions to at least three problems: (1) We need a taxonomic framework for organizing the nearly infinite variety of individual differences that might be measured. (2) We need a common item format, one that is amenable to faithful translation across diverse languages. And, (3) we need a mode of communication--an effective logistical procedure for investigators to easily obtain the items and the findings from previous studies, as well as the data for reanalyses; in addition, we need a way for investigators to add new items to the pool, along with findings about their properties. For the first time, the solutions to all three problems may now be at hand.
Expanded project rationales are provided in the following two scientific reports:
Goldberg, L. R. (1999). A broad-bandwidth, public domain, personality inventory measuring the lower-level facets of several five-factor models. In I. Mervielde, I. Deary, F. De Fruyt, & F. Ostendorf (Eds.), Personality Psychology in Europe, Vol. 7 (pp. 7-28). Tilburg, The Netherlands: Tilburg University Press.
Goldberg, L. R., Johnson, J. A., Eber, H. W., Hogan, R., Ashton, M. C., Cloninger, C. R., & Gough, H. C. (2006). The International Personality Item Pool and the future of public-domain personality measures. Journal of Research in Personality, 40, 84-96.
For other IPIP-related reports, go to: http://www.ori.org/lrg/