Correspondence - letters concerning standards of GED testing, educational accountability - General Educational Development tests - Letter to the Editor

Education Next, Wntr, 2003

Testing the GED

In his article on the high-school graduation rate ("Tassels on the Cheap, Feature, Fall 2002), Duncan Chaplin implies that the General Educational Development (GED) tests represent a lower academic hurdle than graduating from high school. He is simply wrong,

To earn a GED, candidates must pass five separate tests covering math, science, reading, writing, and social studies. The score necessary to pass does not reflect a minimum level of academic achievement; in fact, the passing standard is now set so that 40 percent of all high-school graduates would fail the test.

The GED is designed to document whether a student has mastered a level of knowledge roughly comparable to that of high-school graduates. It makes no promises about lifetime earnings, participation in post-secondary education, or job satisfaction. No test would ever make such promises. But what it purports to do, the GED does very well.

The GED Testing Service (a program of the American Council on Education) strongly encourages students to stay in school and graduate. For many, however, this may not be an option. For them, the GED tests offer an academically rigorous second chance.

MICHEL BAER

American Council on Education Washington, D.C.

Duncan Chaplin responds: I agree that the GED provides an important second chance to adults without a regular degree. However, equating the GED with a regular degree does a great disservice to teenagers, since GED recipients are far less likely to complete college and earn far less on the labor market than those with regular degrees.

Even Baer's claim that GED recipients have similar academic skills is highly suspect. It is true that a random sample of high-school seniors who were likely to graduate were given a GED, and 40 percent did not pass. However, unlike actual GED recipients, none of this random sample had an incentive to pass, took it multiple times, or prepared for the test. The fact that many did not pass is hardly surprising.

Margin of error

Dale Ballou ("Sizing Up Test Scores," Forum, Summer 2002) sounds legitimate warnings about some potential problems associated with using value-added assessment as a way of evaluating schools and teachers. However, if appropriate analytical strategies are used, value-added assessment need not pose the dire risks that his article implies.

First, Ballou overstates the risk to value-added assessment that comes from the question of whether or not scales can be developed with equal intervals. There is no unanimity of opinion on this subject within the psychometric community, as the article implies. There is one school of thought that says equal-unit scales can be developed and used. However, whether a "pure and perfect" equal-unit scale exists is not the critical question. The question should instead be, "If scales from a testing regime are used within a value-added process, is there evidence that measures of student progress are influenced by the distribution of student achievement levels in schools or classrooms because of a lack of equal-interval scales?" After appropriate analytical investigation, if evidence arises that measures of student progress are indeed influenced by positions on the scales, then statistical accommodation would be required within the value-added modeling process. I agree with Ballou's warning. However, I suggest that, i f the empirical evidence points to a problem, there are appropriate analytical solutions to the problem.

Those who do not possess some basic statistical knowledge can easily misconstrue the part of the article that asserts that measures of gain innately have more noise than raw scores, A very basic statistical fact is: the variance of a difference between two variables is equal to the sum of the variances minus two times the covariance between the two variables. This is why, in our modeling efforts, we do massive multivariate, longitudinal analyses in order to exploit the covariance structure of student data over grades and subjects to dampen the errors of measurement in individual student test scores. This leads to an improved ability to distinguish the effectiveness of various schools and teachers. However, even with the most sophisticated statistical approaches, for some subjects and grades the ability to differentiate among educators may allow only a small number of schools and teachers to be identified as being different from the average educator. This should not be considered an obstacle to the deployment of value-added measures as a component of teacher and school evaluations, but as an attribute that allows the data to be used consistent with the reliability of the indicators that can be gleaned from them.

Ballou's cautions are appropriate. However, they do not lead to the judgment that value-added assessment for purposes of evaluating teachers and schools is invalid.

WILLIAM L. SANDERS

SAS Institute, Inc.

Cary, N.C.

Dale Ballou responds: Responses to my article on value-added assessment suggest that it may be useful to put my arguments in a broader context.