There are many GMAT student-aspirants, who do not have clear idea about the Reliability and Validity of GMAT Scores. This page will give the relevant information to those aspirants.
First and foremost thing to remember is the GMAT test scores are not precise measures. Even the best possible test can provide no more than an estimate of a test taker's abilities. Because they are estimates, test scores (like other measures) are subject to a certain amount of chance variation that is inherent in the measurement process itself.
If an individual takes the GMAT examination more than once, he or she is unlikely to receive the same scores each time. It is not possible to determine whether the scores a test taker earns are higher or lower than his or her true performance. However, the chance variation can be estimated statistically and given a value known as the standard error of measurement. The current standard error of measurement for the GMAT Total score is 29. This means that chances are two out of three that the reported GMAT Total score is within 29 points above or below a score reflecting true performance. The standard error of measurement for the Verbal section is 2.8, and for the Quantitative section, 3.0.
Reliability indicates the degree to which a test taker would keep the same score if he or she were to take the test more than once. The average reliability for the GMAT Total score is .92. Perfect reliability is 1.00. Average reliability is.90 for the Verbal score and .89 for the Quantitative score. Therefore, the reliability of the GMAT score accurately reflecting abilities is very high.
The validity of GMAT scores can be described as the degree to which the scores relate to or predict first-year grades in graduate management programs. Since 1978, GMAC has conducted many studies of the validity of GMAT scores. In all studies, GMAT scores, undergraduate grade point averages, and average grades for the first year of graduate school were obtained.
The most recent validity studies indicate that the average correlation between GMAT Verbal, Quantitative, and Analytical Writing Assessment (AWA) scores and mid-program graduate management school grades was 0.48 (a 1.0 indicates perfect accuracy of prediction). The median correlation between undergraduate grade point average (GPA) and first-year graduate management school grades was 0.28. When GMAT scores were combined with undergraduate GPA, the median correlation was 0.53.
These results indicate that GMAT scores are generally better than undergraduate GPAs for predicting average grades in the first-year of graduate management school. However, the best predictor is obtained by combining GMAT scores and the undergraduate GPA.