Different tests use different methods of scoring based on different
needs. The following table summarizes the three main categories of test
scores:
Score
|
How Score is Determined
|
Uses
|
Potential Drawbacks
|
Raw Score
|
By counting the number (or
calculating a percentage) of correct responses or points earned.
|
Often used in teacher-developed
assessment instruments.
|
Scores may be difficult to interpret
without knowledge of how performance relates to either a specific
criterion or a norm or group.
|
Criterion-referenced Score
|
By comparing perfoomance to one or
more criteria or standards for success.
|
Useful when determining whether
specific instructional objectives have been achieved. Also useful
when determining if basic skills that are prerequisites for other
tasks have been learned.
|
Criteria for assessing mastery of
complex skills may be difficult to identify.
|
Age or Grade Equivalent (norm-referenced)
|
By equating a student's performance
to the average performance of students at a particular age or grade
level.
|
Useful when explaining
norm-referenced test performance to people unfamiliar with standard
scores.
|
- Scores are frequently misinterpreted, especially by parents.
- Scores may be inappropriately used as a standard that all
students must meet.
- Scores are often inapplicable when achievement at the
secondary level or higher is being assessed.
- Do not give a typical range of performance for students at
that age or grade.
|
Percentile Rank (norm-referenced)
|
By determining the percentage of
students at the same age or grade level who obtained lower scores.
|
Useful when explaining
norm-referenced test performance to people unfamiliar with standard
scores.
|
Scores overestimate differences near
the mean and underestimate differences at the extremes.
|
Standard Score (norm-referenced)
|
By determining how far the
performance is from the mean (for the age or grade level) with
respect to standard deviation units.
|
Useful when describing a student's
standing within the norm group.
|
Scores are not easily understood by
people without some knowledge of statistics.
|