Reliability
When selecting an IQ test to
administer, one must consider the reliability of the testing. Reliability is defined as the coherence of
the instrument in conjunction with the information collected using said
instrument as the data is gathered over time.
It is the repeatability of the measurement which determines the degree
to which the test is consistently effective (Russ-Eft & Preskill, 2009). Additionally, when estimating reliability
various components should be considered.
Such factors include the differences between
observed scores and true scores, how standard errors of measurement and
reliability coefficients provide indicators of reliability, how reliability is
estimated, and the various factors that can affect the reliability of a test. The following discussion expounds on these
topics.
First, as
part of the IQ test selection process observed scores and true scores ought to
be defined. Observed scores consist of
every measurement taken for each test, whereas the true score marks the
constant measure. Furthermore, each
observed score contains the true score in addition to a degree of error (Thorndike
& Thorndike-Christ, 2009). A test example is a typing assessment. Typically, an individual’s words per minute
(wpm) are recorded. If an individual is
applying for various administrative assistant jobs, undoubtedly they are
required to repeatedly complete a typing test for speed and accuracy. Each of the test scores exhibits observed
scores, as the constant wpm represents his or her true score.
Second, in
relation to reliability, standard errors of measurement and reliability
coefficients are imperative. The standard
error of measurement refers to the typical discrepancy of measurement among
scores. More specifically, this expresses
the common repeated measures in which the score deviates from the true or
average score (Thorndike & Thorndike-Christ, 2009). Hence, the range
of observed scores is consistent which supports the reliability of the test. Concerning reliability coefficients, a
constant relationship between varying elements throughout testing demonstrates
reliability. Order is maintained from
test to test regardless of the observed scores.
Both concepts, standard error of measurement and reliability
coefficients, are interrelated in estimating reliability. Given time limitations, researchers often
utilize a couple of measurements to approximate the average scores and
deviations as well as the order of the set.
Observance of the scatter sustains reliability. In addition, it
is important to estimate the precision of a score in effort to verify
whether the level of variability is due to errors in measurement versus an
inconsistency in true scores. Also, this
process “represents a more exacting definition of the test’s ability to
reproduce the same score (Thorndike &
Thorndike-Christ, 2009, p. 137).
The final points of discussion are
the factors affecting reliability and the correlation
between reliability and the level of confidence one can place on an individual’s
score. In general, there are four
factors affecting reliability; variability of the group, level of the group on
the trait, length of the test, and operations used for estimating the
reliability. First, variability of the
group refers to the consistency of order.
In cases in which order is maintained, the reliability coefficient is
more precise. However, if the order
varies from test to test, reliability is adversely affected. Second, the level of the group on the trait
regards the experience or proficiency of participants in relation to the
featured characteristic. Hence, test
accuracy may vary considering field goal percentages among a group of high
school basketball shooting guards versus field goal percentages of a group of
NBA shooting guards. The third factor
affecting reliability is the length of the test. Generally, the longer the test the more
accurate the scores are due to the fact that mannerisms or performance are
repetitively displayed. Last of these,
operations used for estimating reliability are critical. In short, various methods of testing provide
varying levels of reliability (Thorndike & Thorndike-Christ, 2009). Now, in regard to
reliability and confidence, there is a direct correlation. The more reliable the test, the more confidence
one can place on an individual’s score.
Thus, an unreliable test results in less confidence concerning the
accuracy of the outcome.
References
Russ-Eft, D.,
& Preskill, H. (2009). Evaluation in organizations: A systematic
approach
to enhancing
learning, performance, and change (2nd ed.). New York:
Basic Books.
Thorndike, R. M.
& Thorndike-Christ, T. M. (2009). Measurement and evaluation in
psychology and
education (8th ed.). Upper Saddle River, NJ:
Prentice Hall.
