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Guidelines for Re-testing with the TABE, Forms 7/8

ABE programs across Massachusetts have encountered difficulty in determining when retesting using different TABE levels is appropriate and when students' observed scores are a reasonably accurate reflection of their abilities.

To recap the situation with the TABE, students are first administered a Locator test consisting of 15-18 items depending on subject area. The number-correct score obtained by a student on the Locator determines the level of the TABE Complete Battery test in a particular subject area to be administered. For each subject area, the Complete Battery has Easy, Medium, Difficult, and Advanced levels, each level consisting of progressively difficult test items.

The problems that are emerging in many ABE programs with regard to the TABE involve assignment to levels by the Locator test and the reliability and validity of scores from the Complete Battery. ABE instructors noted that the Locator test scores resulted in varying degrees of accuracy for predicting the appropriate Complete Battery test level. This was confirmed by the Center for Educational Assessment staff at UMASS Amherst. Massachusetts ABE instructors contacted ACLS for guidance as to when it is appropriate to retest students and when scores are a reasonable assessment of students' abilities, and UMASS staff have provided this guide below.

To determine whether a student's score on any section of the Complete Battery is a reasonable reflection of that student's ability, please do the following.

• First, determine which of the following six charts fits the Form (either 7 or 8) and Test Subject (Reading, or Language, or Applied Mathematics) you administered to a student.
• Once you have chosen the correct chart, find the student's number-correct score for the difficulty level (Easy, Medium, Difficult, or Advanced) you administered to the student.
• For each possible number-correct score, you will be directed to one of three options: retest using an easier difficulty level of the TABE, not retest at all, or retest using a more difficult level of the TABE.

The guidelines presented in Figures 1-6 | were developed given careful statistical consideration of the standard error of measurement (SEM) ¹. The SEM is a statistical estimate of the amount of error to be expected in a particular score from a particular test, and provides the user with a range within which a student's true score is likely to fall. Lower SEM is associated with more precise measurement, while higher SEM means that an individual's score contains more error and is more unreliable. For this reason, SEM is one reasonable indicator of the reliability of test results. An individual student's observed score from a single testing experience is likely to fall within one SEM of the student's true score 68% of the time, and within two SEMs 95% of the time. The guidelines in Figures 1-6 are computed using the statistical properties of the tests to ensure that decisions as to whether or not students should be retested are based on the statistical levels of errors in the scores.

¹ SEM is computed as where SD is the standard deviation of the test and r is the reliability. For TABE, reliability coefficients provided by the publisher are KR-20 estimates of internal consistency. SDs were taken from Table 8 of the TABE Technical Report, while KR-20 estimates are from Tables 10-26.