Typically, conventional intelligence tests correlate about 0.4 to 0.6 (on a 0 to 1 scale) with school grades, which statistically speaking is a respectable level of correlation. A test that predicts performance with a correlation of 0.5, however, accounts for only about 25 percent of the variation in individual performances, leaving 75 percent of the variation unexplained. Thus, there has to be much more to school performance than IQ.
The predictive validity of the tests declines when they are used to forecast outcomes in later life, such as job performance, salary or even obtaining a job in the first place. Generally, the correlations are only a bit over 03, meaning that the tests account for roughly 10 percent of variation in people’s performance. That means 90 percent of the variation is unexplained. Moreover, IQ prediction become less effective once populations, situations or tasks change. For instance, Fred Fiedler found that IQ positively predicts leadership success under conditions of low stress. But in high-stress situations, the tests negatively predict success. Some intelligence tests, including both the Stanford-Binet and Wechsler, can yield multiple scores. But can prediction be improved?
Curiously, whereas many kinds of technologies, such as computers and communications, have moved forward in leaps and bounds in the U.S. around the world, intelligence testing remains almost a lone exception. The content of intelligence tests differs little from that used at the turn of the century. Edwin E. Chiselli, an American industrial psychologist, wrote an article in 1966 bemoaning how little the predictive value of intelligence tests had improved in 40 years. More than 50 years later the situation remains unchanged.
We can do better. In research with Michael Ferrari of the University of Pittsburgh, Pamela R. Clinkenbeard of the University of Wisconsin-Whitewater and Elena L. Grigorenko of Yale University, I showed that a test that measured not only the conventional memory and analytical abilities but also creative and practical thinking abilities could improve prediction of course grades for high school students in an introductory psychology course. (A direct comparison of correlations between this test and conventional tests is not possible because of the restricted sample, which consisted of high-ability students selected by their schools.)
In these broader tests, individuals had to solve mathematical problems with newly defined operators (for example, X glick Y = X + Y if X < Y, and X - Y if X3 V), which require a more flexible kind of thinking. And they were asked to plan routes on maps and to solve problems related to personal predicaments, which require a more everyday, practical kind of thinking.
55- What is the passage mainly concerned with?