Saturday, June 06, 2009

WMF Human Cognitive Abilities Project critical update: Carroll's EFA final solutions now being posted

The WMF Human Cognitive Abilities (HCA) project is pleased to announce the addition, to the WMF HCA Archive, the final hierarchical factor matrix solutions (produced by Jack Carroll) for each exploratory factor analysis included in his seminal 1993 Human Cognitive Abilities book.

When Carroll's (1993) book was first published, individuals could purchase (from Cambridge University Press), a set of two 5.25 disks. Many researchers were very excited when they heard this news and many purchased the disks. Much of our initial excitement was dampened when the disks arrived--- as they did not include the original correlation matrix input files. However, they did contain the hierarchical factor matrix final solution Carroll produced for each dataset he had analyzed.

Since Feb 2008 these disks can no longer be purchased from the publisher. Thus, researchers are now unable to examine the final output solutions from Carroll's methods (described in detail in Chapter 3, p. 73 - 114).

Also, if you happened to purchase the disks, the output could only be printed on old dot-matrix type printers (and not all such printers). Each file, when viewed in a text editor, is filled with all kinds of strange printer codes and characteristics that result in the output, when printed on today's printers, being a mess. Fortunately, when the HCA project was first started, I (Kevin McGrew) had someone write a small computer utility that cleaned the files of the strange code--thus making it possible to print the solutions. At that time we printed all the solutions and assembled them in three ring binders. The printed output was not perfectly formatted, but it was readable.

The WMF HCA project is pleased to announce that we have scanned all these printed copies to PDF files. We are adding these PDF files to each dataset when they are posted to the WMF HCA archive. Unfortunately, some of the printed output files have been lost or were not originally printed. And, we can no longer find the software utility used to clean the files for printing on contemporary printers. Thus, we do not have all the Carroll EFA hierarchical matrix output solutions available at this time. We will attempt to have a similar file cleaning/printing utility developed to extract these final output files.

Why is this important?

In cases where we have archived the original correlation matrix, original publication, and Carroll's hierarchical output solution, it is now possible for independent researchers to conduct their own secondary analysis of the original matrix and compare it to Carroll's solution. More importantly, and following the recommendation of Carroll, these "final" EFA solutions can serve as input into contemporary CFA/SEM software to refine the solution. Many researchers were not aware that this was the procedure Jack Carroll was using near the end of his career. He was using his custom written EFA software (as explained in Chapter 3 of his book) to secure an initial factor structure for a dataset which he then used as the starting point for model generation, exploration and evaluation via CFA/SEM methods. An example of this can be seen in the last chapter Carroll published (click here to see a pre-pub version of this chapter)

We hope that the inclusion of the final Carroll hierarchical matrix output files will encourage researchers to revisit Carroll's analyses with an eye towards a fine-tuning of his work--something he encouraged in his 1993 book and subsequent writings. Individuals will need to read Chapter 3 in Carroll (1993) to understand and interpret the EFA hierarchical output files.

Finally, the availability of the EFA hierarchical matrix PDF output files is designated with a large red check mark on each datasets heading (or mindmap branch if you are viewing the archive in the visual-graphic map mode).

Technorati Tags: , , , , , , , , , , , , , ,

No comments: