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Validity and Reliability
in Assessments
Validity and reliability are very important in regards to assessments.
At times, however, these terms can be somewhat confusing. According
to Robert L. Linn and Norman E. Gronlund, authors of Measurement and
Assessment in Teaching, " Validity is "...an evaluation of the adequacy
and appropriateness of the interpretations and uses of assessment results"
(2000). These same authors state, "Reliability refers to the consistency
of assessment results" (2000). So, what is the difference between
the two terms?
Briefly, the authors state that "...validity is always concerned with
the specific use of assessment results and the soundness and fairness of
our proposed interpretations of those results" (2000). In other words,
how are the results being used? Linn and Gronlund pose this example,
"...if a state- or district mandated test led teachers to ignore important
content not covered by the test, that consequence should be taken into
account in judging the validity of that test use" (2000). This is
an example of what may happen in composition classes around the state of
Illinois. To explain, since the PSAE writing test does not test descriptive
or narrative writing ability, many English teachers around the state may
ignore these skills and concentrate only on teaching expository and persuasive
writing techniques. If this happens, it puts the validity of the
PSAE into question.
As for test reliability, as mentioned above, it is important to look
at the "...consistency of assessment results" (2000). There
are basically two things to examine in order to determine the reliability
of a give assessment. To confirm consistency, one must test the same
group of students on at least two separate dates, using the same test.
As the authors state, "If we obtain quite similar scores when the same
assessment procedure is used with the same students on two different occasions,
we can conclude that our results have a high degree of reliability from
one occasion to another" (2000). A second check to examine reliability
is possible if separate instructors test the same students, using the same
assessment on different days. As Linn and Gronlund state, if these teachers
"...obtain similar ratings, we can conclude that the results have a high
degree of reliability from one rater to another" (2000). The ACT
testing and the PSAE writing assessment procedures provide opportunities
to prove or disprove the reliability of the tests. For example, the
PSAE writing test is assessed by 2-3 graders. If all end up with
the same or similar ratings for essays, it is most likely a reliable test.
Another way to check reliability is by comparing the results of ACT practice
tests to those of the official ACT tests. If it is a reliable test,
we can assume that the scores of the students who practice taking the test
will improve over a given period of time (2000).
As mentioned, validity and reliability are essential in regards to assessments.
Both examine the results of a given assessment. While they are closely
related, they do have individual characteristics that distinguish each
from the other. |