1 2 3 4
Stan 5 ines
6 7 8 9
4% 7%
Percent in
12% 17%
Stan
20%
ines
17% 12% 7% 4%
Figure 2: A normal distribution curve showing corresponding
standard scores and percentiles.
SELF ASSESSMENT EXERCISE
1. What is test interpretation and why is it necessary to interpret classroom test?
2.
Highlight the major difference between criterion-reference interpretation and Norm-referenced interpretation.
3. What are the main advantages of stanine scores over grade
norms?
ANSWER TO SELF ASSESSMENT EXERCISE
A1: Test interpretation is a process of assigning meaning and
usefulness to the scores obtained from classroom test. It is necessary to interpret classroom test because the raw score obtained from a test standing on itself rarely has meaning. The
scores on their own lack a true zero point and equal units. Hence
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it is not possible to take reliable academic and psychological
decisions on the basis of the raw scores.
A2: The major difference between criterion referenced interpretation
and norm referenced interpretation is that Criterion-referenced interpretation is the interpretation given to raw score by converting it into a description of the specific tasks that the testee
can perform; while Norm-referenced interpretation is the interpretation given to raw score by converting it into some type of derived score that indicates the testee relative position in a
clearly defined referenced group.
A3: The main advantage of stanines scores over grade norms is that stanine scores as standard scores provides equal units that can be treated arithmetically and any given raw score in the reference group can be described by reference to the stanine within which it
falls. The ease with which stanines are converted to other standard scores makes its interpretation easy and it is also possible to compare an individual’s performance based on a common group. Whereas the grade norms merely describe test
performance in terms of the particular grade or age group in which the testee’s raw score is just average. Moreover depicting
test performance in terms of grade equivalent can lead to unsound decisions because of the inequality of the units and the invalid
assumptions on which they are based.
4.0 CONCLUSION
In this unit you learned how to interpret test scores. This includes criterion-referenced and norm-referenced interpretation such as the age
and the grade norms. You also learn test interpretation based on standard scores norms utilizing the normal curve and the standard deviation units such as the z-scores, the T – scores and stanine norms. In addition you
learned about the percentile norms and the comparison between the
score systems.
5.0 SUMMARY
Test interpretation is a process of assigning meaning and usefulness to the scores obtained from classroom test. This is because the test
scores on their own lack a true zero point and equal units.
Criterion-referenced interpretation is the interpretation of test raw score based on the conversion of the raw score into a description of
the specific tasks that the learner can perform.
Norm-referenced interpretation is the interpretation of raw score
based on the conversion of the raw score into some type of derivedscore that indicates the learner’s relative position in a clearly defined
reference group.
Norms are referenced frames on which interpretation of test scores are based. They represent the typical performance of the testees in
the reference frame on which the test raw scores were standardized.
Grade norms are reference frame work for interpreting the academic achievement of learner’s in the elementary schools. They represent
the typical performance of specific groups such as a class.
Age norms like the grade norms are based on the average scores earned by pupils of different ages and are interpreted in terms of age
equivalents.
Percentile norms are test norms that deal with percentile ranks or scores. They are use for comparison of percentage of group to which
individual belongs.
A percentile rank (or score) describes a learner’s performance in terms of the percentage of learners in some clearly defined group that
earn lower scores.
Standard score is a method of indicating a testee’s relative position in a group by showing how far the raw score is above or below average.
Standard scores express test performance in terms of standard
deviation units from the means.
The normal curve is a symmetrical bell-shaped curve that has many useful mathematical properties utilized in test interpretation using
standard scores.
The Z-score is a simple standard score which expresses test performance simply and directly as the number of standard deviation
units a raw score is above or below the mean.
The T – score refers to any set of normally distributed standard
scores that has a means score of 50 and a standard deviation of 10.
The stanine is a kind of standard score which divides a population according to some proportions into nine parts numbered 1 to 9. It has a mean score of 5 and a standard deviation of 2 . Each stanine corresponds to a score or a range of scores. Each individual’s score falls within a stanine and such score can be described by reference to
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the stanine within which it falls. Stanines are widely used for local
norms because of the ease with which they can be computed andinterpreted.
6.0 TUTOR MARKED ASSIGNMENT
1.
With the help of a table present the most common types of test norms for education and psychological tests. For each type of test name the derived score, type of comparison undertaken, type of group used and the meaning in terms of test performance.
2. What is T-score?
3.
A test has a mean score of 40 and a standard deviation of 4.
What are the T – scores of two testees who obtained raw scores of 30 and 45 respectively in the test?
4.
What are the limitations of the Percentile rank? How were these limitations overcome in Stanine
scores?7.0 REFERENCES/FURTHER READINGS
Gronlund, N.E (1985), Measurement and Evaluation in Teaching. New York:Macmillan Publishing Company.
Kerlinger, F.N (1973), Foundations of Behavioural Research. Holt,
Rinehart and Winston Inc. New York:
Thorndike, R.L and Hagen, E.P (1977). Measurement and Evaluation in Psychology and Education. New York: John Wiley and Sons;