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Educational Assessment of Students Eighth Edition
Chapter 17 Interpreting Norm- Referenced Scores
Copyright © 2019, 2015, 2012 Pearson Education, Inc. All Rights Reserved
Copyright © 2019, 2015, 2012 Pearson Education, Inc. All Rights Reserved
Key Concepts (1 of 2)
17.1 A referencing framework is a structure used to compare a student’s performance to some-thing external to the assessment in order to interpret performance. A norm-referencing framework interprets a student’s assessment performance by comparing it to the performance of a well-defined group of other students who have taken the same assessment. A criterion-referencing framework interprets a student’s performance according to the kinds of performances a student can do in a domain. A standards-referenced framework combines elements of both. Test publishers may provide norm-referenced scores based on information from several different norm groups. Use normative information to describe student strengths, weak-nesses, and progress.
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Key Concepts (2 of 2)
17.2 Different types of norm-referenced scores are constructed to serve different purposes. The percentile rank tells the percentage of the students in a norm group who have scored lower than the raw score in question. A linear standard score tells how far a raw score is from the mean of the norm group, expressing the distance in standard deviation units.
17.3 A normal distribution is a mathematical model (an equation) based on the mean and standard deviation of a set of scores. Normalized standard scores are based on transforming raw scores on an assessment to make them fit a normal distribution. Developmental and educational growth scales are norm- referenced scores that can be used to chart educational development or progress. An extended normalized standard score tells the location of a raw score on a scale that is anchored to a lower grade reference group. A grade- equivalent score tells the grade level at which a raw score is average.
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Norm- versus Criterion-Referencing
• A norm-referencing framework interprets a student’s assessment performance by comparing it to the performance of a well-defined group of other students who have taken the same assessment.
• A criterion-referencing framework interprets a student’s performance according to the kinds of performances a student can do in a domain.
• A standards-referenced framework combines elements of both.
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Norm Groups
• Local norm group: students in the same grade in the same school district
– Schools/districts should have scores – Publishers may offer scores
• National norm group: intended to be representative of students in the country
– Test publishers use different norming procedures
• Special norm group
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School Averages Norms
• School averages norms: ranked tabulation of the average (mean) score from each school building in a national sample of schools
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Guidelines for Using Publishers’ Norms
• Make sure the norm group is: – Relevant – Representative – Recent
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Percentile Rank
• The percentile rank tells the percentage of the students in a norm group who have scored lower than the raw score in question.
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Percentile Ranks: Advantages
• Easily understood.
• Clearly reflect norm-referencing.
• Permit a person’s performance to be compared to a variety of norm groups.
• Can be used to compare a student’s relative standing in each of several achievement or ability areas.
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Percentile Ranks: Limitations
• Can be confused with percentage correct scores.
• Can be confused with some other types of two-digit derived scores.
• Do not form an equal-interval scale.
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Linear Standard Score
• A linear standard score tells how far a raw score is from the mean of the norm group, expressing the distance in standard deviation units.
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Z Scores
• Communicate students’ norm-referenced achievement expressed as a distance away from the mean.
– if Z = −1.5, the student’s score is 1.5 standard deviations below the average score.
• Can be used for norm-referenced comparison of raw scores with different metrics
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SS Scores
• Tells the location of a raw score in a distribution having a mean of 50 and a standard deviation of 10.
– Transformation of z score – Example: If Z = −1.5, SS = 35
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Normalized Standard Scores
• A normal distribution is a mathematical model (an equation) based on the mean and standard deviation of a set of scores.
– Normal curves are smooth, continuous, symmetrical, and bell shaped
• Normalized standard scores are based on transforming raw scores on an assessment to make them fit a normal distribution.
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Normalized z -Scores
• z-scores that have percentile ranks corresponding to what we would expect in a normal distribution
Raw Score Percentile rank
Normalized standard (zn)
Linear standard (z)
36 98 2.05 2.43 33 96 1.75 1.64 15 4 −1.75 −3.09 14 2 −2.05 −3.36
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Normalized T-scores
• Tell the location of a raw score in a normal distribution having a mean of 50 and a standard deviation of 10.
– Example: Joey’s T-score is 40, which means he is one standard deviation below the mean of the norm group, and his percentile rank is approximately 16.
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Deviation IQ Scores
• Tells the location of a raw score in a normal distribution having a mean of 100 and a standard deviation of 15 or 16.
– Example: Meghan has DIQ = 116, which means she has scored one standard deviation above the mean of her age group and the percentile rank of her score is 84.
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Stanines
• Tells the location of a raw score in a specific segment of a normal distribution.
– Example: Blake’s stanine on the spelling subtest of the standardized test was 3, which means that his raw score was in the lower 20% of the norm group. Specifically, his percentile rank was between 11 and 22.
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SAT-Scores
• Historically, a normalized standard score from a distribution that has a mean of 500 and a standard deviation of 100.
• The SAT program no longer uses this computation, but the current scores on the 200-800 scale can be compared across administrations.
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Normal Curve Equivalents
• NCE scores are normalized standard scores with a mean of 50 and a standard deviation of 21.06.
• Primary value is evaluating gains from various educational programs that use different publishers’ tests
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Developmental and Educational Growth Scales
• Developmental and educational growth scales are norm- referenced scores that can be used to chart educational development or progress.
– Extended normalized standard score scale – Grade-equivalent score scale
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Extended Normalized Standard Score
• An extended normalized standard score tells the location of a raw score on a scale that is anchored to a lower grade reference group.
– Based on extended z scale Or – Based on item response theory
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Grade-Equivalent Score
• A grade-equivalent score tells the grade level at which a raw score is average.
– Useful for reporting educational development. – Provided by test publisher.
▪ GE is the median score (sometimes mean score) in each grade’s norm group.
▪ A third grader’s GE score of 5.7 on a mathematics test covering third-grade content does not mean that this student should be placed in fifth-grade math. Rather, it means that he scored the same as the average 5th grader (7th month) on the third-grade test.
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Things to Keep in Mind When Interpreting Grade Equivalents (1 of 2)
• In some subject areas, students’ performance drops over the summer months.
• The meaning of grade-equivalent scores for a subject depends very much on the subject matter.
• Grade-equivalent scores do not necessarily indicate mastery of the material.
• The more closely the test items match the material emphasized in the classroom before the test was administered, the more likely the students will score well above grade level.
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Things to Keep in Mind When Interpreting Grade Equivalents (2 of 2)
• Grade equivalents from different tests cannot be interchanged.
• Grade equivalents for different subjects cannot be compared.
• Grade equivalents do not indicate “normal” growth.
• The grade-equivalent score scale does not have a one- to-one correspondence with the number of questions a student answers correctly on a test.
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Guidelines for Score Interpretation
• Look for patterns in scores.
• Seek explanations for the patterns.
• Don’t expect many surprises.
• Don’t overinterpret small differences.
• Use evidence from other assessments to clarify interpretations.
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Typical Misunderstandings (1 of 2)
• The grade-equivalent score tells which grade the student should be in.
– They Do Not.
• The percentile rank and percent-correct scores mean the same thing. – They Do Not.
• The percentile rank norm group consists of only the students in a particular classroom.
– It Does Not.
• “Average” is the standard to beat. – It Is Not.
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Typical Misunderstandings (2 of 2)
• Small changes in percentile ranks over time are meaningful.
– They Are Not.
• Percent-correct scores below 70 are failing. – They Are (Usually) Not.
• If you get a perfect score, your percentile rank must be 99.
– It May Not Be.
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Copyright
- Educational Assessment of Students
- Key Concepts (1 of 2)
- Key Concepts (2 of 2)
- Norm- versus Criterion-Referencing
- Norm Groups
- School Averages Norms
- Guidelines for Using Publishers’ Norms
- Percentile Rank
- Percentile Ranks: Advantages
- Percentile Ranks: Limitations
- Linear Standard Score
- Z Scores
- S S Scores
- Normalized Standard Scores
- Normalized z -Scores
- Normalized T - s c o r e s
- Deviation I Q Scores
- Stanines
- S A T-Scores
- Normal Curve Equivalents
- Developmental and Educational Growth Scales
- Extended Normalized Standard Score
- Grade-Equivalent Score
- Things to Keep in Mind When Interpreting Grade Equivalents (1 of 2)
- Things to Keep in Mind When Interpreting Grade Equivalents (2 of 2)
- Guidelines for Score Interpretation
- Typical Misunderstandings (1 of 2)
- Typical Misunderstandings (2 of 2)
- Copyright