The findings were made possible by recent advances in the field of meta-analysis, a method that combines research from individual studies and produces results that are considered more accurate than those from single studies. Specifically, more accurate range-restriction methods have been developed that allow for better factoring of bias in research samples.

When the researchers applied these new methods to the dataset from a recent meta-analysis of the GMAT, they found that “the validity of the GMAT is actually higher” than they thought, says In-Sue Oh, a doctoral candidate at the Henry B. Tippie College of Business at the University of Iowa—and first author of the paper announcing the study results.

In light of the findings, the paper’s authors suggest that the GMAT “should be given greater weight in business school admission decisions and in developing a comprehensive causal model of performance in business school.” They also say that giving the GMAT greater weight “will increase the quality of business school graduate programs through admitting higher quality graduate students.”

One further implication, In-Sue Oh says, is that administrators in business schools and other education policy makers should become familiar with how emerging methodologies in the field of meta-analysis affect our general understanding of tests such as the GMAT.

The paper, entitled “The Graduate Management Admission Test (GMAT) is Even More Valid Than We Thought: A New Development in Meta-Analysis and Its Implications for the Validity of the GMAT,” was published in the December 2008 edition of the journal Academy of Management Learning & Education.