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

Below, we’ll jump into what each of these statistics or scores mean and how these scores will be interpreted by educators and schools. Want more? To get started with all of the Woodcock-Johnson testing material offered by Testing Mom, check out our 100 Free Gifted and Talented Questions.

Level of Development

Age equivalents

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.”

Grade equivalent

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

Standard Score

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.

Percentile Rank

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

The scoring system for these tests is based on three interrelated components: standard scores, percentile ranks, and classifications. Here’s an overview of each component:

• Standard Score: The standard score is a transformation of the raw score (the number of correct responses) on a test. The standard score indicates how a person’s performance on a test compares to that of a reference group, typically people of the same age or grade level. For the Woodcock-Johnson test, the mean standard score is 100 and the standard deviation is 15. This means that a score of 100 represents average performance. A score above 100 is above average, and a score below 100 is below average.
• Percentile Rank: The percentile rank is another way of comparing a person’s test performance to others. A percentile rank of 50, for example, means that the individual scored as well as or better than 50% of the reference group. So, if a child has a percentile rank of 85 on a test, they scored as well as or better than 85% of children their age.
• Classification: Classifications provide a qualitative interpretation of test scores. For the Woodcock-Johnson test, scores are often classified into ranges such as “low average,” “average,” “high average,” “superior,” or “very superior.” These classifications are typically based on standard scores. For example, a standard score of 85-115 might be classified as “average.”

Here’s how the three components are related:

• The raw score from the test is transformed into a standard score.
• This standard score is then used to determine the percentile rank.
• Based on the standard score, a classification is assigned.

For example, a standard score of 85 corresponds approximately to a percentile rank of 16, which would typically be classified as “Low Average.”

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 a 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

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 or her age (average standard score is 100).

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