#^#^#^#^#^#^#^#^# FROM CHUCK TUCKER 941201 #^#^#^#^#^#^#^#^#

I have been using the PCT argument on use of statistics

in the behavioral sciences and today read Stephen Jay

Gould's review of the book in THE NEW YORKER 941128

which states: "Herrnstein and Murray's correlation

coefficients are generally low enough by themselves

to inspire lack of confidence. .... Although low figures

are not atypical for large social-science surveys involving

many variables, most of H and M's correlation are very

weak - often in the 0.2 to 0.4 range. Now, 0.4 may

sound respectably strong, but - and this is the key point -

R2 is the squarre of the correlation coefficient, and the

square of a number between zero and one is less that the

number itself, so a 0.4 correlation yields an r-squared

of only .16. In Appendix 4, then, one discovers that the

vast majority of the conventional measures of R2, excluded

from the main body of the text, are less that 0.1. These

very low values of R2 expose the true weakness, in any

meaningful vernacular sense, of nearly all the relationships

that form the meat of 'The Bell Curve.'" (p. 147) Sound

familiar to anyone!

BTW, Newsweek in their report on this book interpreted R

as R2 and said something like ".4 correlation accounts

for 40% of the variation" - I was amazed.

On Modelling

I would really appreciate it if someday one of you modellers

could provide some instructions for using these model

program for teaching and perhaps research. I think it would

a nice topic for an essay - "How to use ..... "

Regards, Chuck