Publication Date: 2003-09-00
Author: Monetti, David M.; Hinkle, Kerry T
Source: ERIC Clearinghouse on Assessment and Evaluation
Five Important Test Interpretation Skills for School Counselors. ERIC Digest.
School counselors are often asked to administer and interpret norm-referenced tests. Certain fundamental test interpretation skills are necessary to accurately interpret and utilize test data. The purpose of this Digest is to outline five skills that will increase the likelihood that test information is interpreted correctly.
"SKILL 1: UNDERSTANDING WHAT NORM-REFERENCED TESTS ARE AND WHAT THEY DO"
Norm-referenced tests are assessments administered to students to determine
Norm groups can be used to create either national norms or local norms, depending on who is included in the normative sample.
Norm-referenced tests have several strengths. For example, Dombrowski (2003) points out that norm-referenced testing often allows for reliable and objective measurement.
However, with these types of assessments, it is critical to understand
the composition of the norm group (Oosterhof, 2003). It's also important
to note that test scores on
Criterion-referenced and norm-referenced tests yield different, but
Results of norm- and criterion-referenced tests should be combined with other formal and informal data collection methods, since no single set of test scores is adequate to make important educational decisions (Code of Fair Testing Practices in Education, 1988).
"SKILL 2: UNDERSTANDING THE PROPERTIES OF THE NORMAL CURVE"
As previously discussed, in norm-referenced tests, a child's test performance
Knowing the mean helps the test interpreter to identify the average performance of the norm group, but is not sufficient to correctly interpret an individual's performance on a norm-referenced test. The school counselor also must know how the concept of standard deviation is related to the normal curve. Drummond (2000) indicates that standard deviation is a statistic that defines the spread of scores around the mean.
Standard deviation helps determine how far above or below the norm group mean an individual's score falls. For practical purposes, the normal curve is divided into three standard deviations above the mean and three standard deviations below the mean. In a normal curve, 34% of individuals fall between the mean and one standard deviation above the mean, 14% of individuals fall between one standard deviation above the mean and two standard deviations above the mean, and 2% of individual fall between two standard deviations above the mean and three standard deviations above the mean. Since the normal curve is symmetrical, the percentages are the same for the standard deviations above and below the mean.
"SKILL 3: KNOWING THE PROPERTIES OF COMMON SCORE TYPES"
To accurately and efficiently interpret norm-referenced assessments, school counselors need to be familiar with the properties of common scores they may encounter. Those score types are Z scores, T scores, NCE scores, and stanine scores.
* Z scores have a fixed mean of 0 and a standard deviation of 1. Thus, if a student's test performance is one standard deviation above the mean, the individual has a Z score of 1. If a student's test score is two standard deviations below the mean, his or her Z score is a -2. It is possible(and common) for students to have negative Z scores.
* T scores often have a mean of 50 and a standard deviation of 10. Thus, if a student's test performance is one standard deviation below the mean, the individual has a T score of 40. If a student's test score is at the mean, his or her T score is 50.
* NCE scores stands for normal curve equivalent scores. NCE scores have
* Stanine scores have a fixed mean of 5 and a standard deviation of
2. The term
"SKILL 4: RECOGNIZING THE DIFFERENCE BETWEEN PERCENT AND PERCENTILE"
School counselors need to recognize that percent and percentile are different concepts.
The term "percent" is an abbreviation of the Latin phrase per centum,
"SKILL 5: BEING ABLE TO TRANSLATE FROM ONE STANDARD SCORE TO ANOTHER"
Once school counselors have developed competency with the four skills
Because the score types discussed above (Z, T, NCE, stanine) are all
based on the
Eighty-four percent of the norm group performed at or below the test taker's score. Thestudent also had a T score of 60, an NCE score of 71, and a stanine score of 7. All of the scores are one standard deviation above the mean. The same is true for students who have scores that fall below the mean. If a student's norm-referenced test score is two standard deviations below the mean, the corresponding Z score is -2, the T score is 30, the NCE score is 8, and the stanine is 1. Table 1 will help translate four common standard score types.
Due to the increased reliance on norm-referenced tests in schools, it
is essential that
Bond, L. A. (1996). Norm- and criterion-referenced testing. Practical
Code of Fair Testing Practices in Education. (1988) Washington, DC: Joint Committee on Testing Practices.
Dombrowski, S. C. (2003). Norm-referenced versus curriculum-based assessment: A balanced perspective. Communique, 31 (7): 16-20.
Drummond, R. J. (2000). Appraisal procedures for counselors and helping professionals (4th ed.). Upper Saddle River, NJ: Merrill Prentice Hall.
Linn, R. L., Graue, M. E., & Sanders, N. M. (1990). Comparing state
and district results to national norms: The validity of the claims that
"everyone is above average."
Oosterhof, A. (2003). Developing and using classroom assessments (3rd ed.). Upper Saddle River, NJ: Merrill Prentice Hall.
Popham, W. J. (2002). Classroom assessment: What teachers need to know
(3rd ed.). Boston, MA: Allyn and Bacon.
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