How is the Woodcock-Johnson Scored?
Three types of statistics or scores are generated by the Woodcock Johnson-IV.
- level of development
- comparison with peers
- degree of proficiency
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Level of Development
An age equivalent (AE) or age score, reflects the child’s performance in terms of age level in the norming sample at which the average score is the same as the child’s score. For example, if a child named Sam is 8 years old and receives an AE of 12.1 on a particular test, the correct interpretation would be, “Test results indicate that Sam’s performance on this test is comparable to that of an average 12 year old.”
A grade equivalent (GE), or grade score, likewise reflects the child’s performance in terms of the grade level of the norming sample at which the average score is the same as the child’s raw score. For example, if a child named Rita, a 7th grader, received a GE of 6.5 on the Reading Fluency test, the correct interpretation would be, “Rita is a 7th grader who currently performs at the mid-sixth grade level in reading fluency.”
Comparison with Peers
The standard score (SS) on the WJ-IV describes a child’s performance relative to the average performance of the comparison group. The scale is the same as the IQ test. In other words, the average standard score is 100 with a standard deviation of 15. For example, if a child named John had a standard score of 85 in the calculation test, he would be functioning in the low average range for that particular skill.
A percentile rank (PR) describes a child’s relative standing to his or her peers on a scale of 1 – 100. Thus, a percentile rank of 6 would indicate that only 6 children out of a hundred in a comparison group (similar age and education level) would score as low or lower.
Relationship Between Standard Score, Percentile Rank, and Classification
|Score Range||Percentile Rank||Range Classification|
|131 and above||98 to 99.9||Very Superior|
|121 to 130||92 to 97||Superior|
|111 to 120||76 to 91||High Average|
|90 to 110||25 to 75||Average|
|80 to 89||9 to 24||Low Average|
|70 to 79||3 to 8||Low|
|69 and below||0.1 to 2||Very Low|
Degree of Proficiency
Relative Proficiency Index (RPI) This statistic is particularly useful in predicting the child’s adjustment to a particular academic program. The RPI predicts a child’s level of proficiency on tasks that typical age or grade peer would perform with 90% proficiency. For example, suppose a particular child generated a RPI of 55/90 on the calculation test. This means that, on similar math tasks, the child would demonstrate 55% proficiency, whereas the same age or grade peer would demonstrate 90% proficiency. Please note the denominator in the RPI is always 90 (representing 90% efficiency on the test or task) whereas the numerator varies from 0 – 100 and represents how proficient the particular child tested is on that task. Table two presents the interpretations of RPI scores.
Interpretation of RPI Scores
|Reported RPIs||Functionality||Implications for Academic Achievement|
|100/90||Very Advanced||Extremely Easy|
|98/90 to 100/90||Advanced||Very Easy|
|95/90||Within Normal Limits to Advanced||Easy|
|82/90 to 95/90||Within Normal Limits||Manageable|
|67/90 to 82/90||Mildly Impaired to Within Normal Limits||Difficult|
|24/90 to 67/90||Mildly Impaired||Very Difficult|
|3/90 to 24/90||Moderately Impaired||Extremely Difficult|
|0/90 to 3/90||Severely Impaired||Impossible|
AE = Age Equivalent
The child’s performance on a particular task is presented in terms of the age level of an average performance on that task.
GE = Grade Equivalent
The child’s performance on a particular task is presented in terms of the grade level of an average performance on that task.
Easy to Diff = Easy to difficult
This statistic provides the age range of what the child would find easy to very difficult on a particular academic task.
RPI = Relative Proficiency Index
This statistic provides the level of proficiency on a particular task. SS = Standard Score This statistic compares the child’s performance to others of his age (average standard score is 100).
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