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TOOLS OF ASSESSMENT
Celine Espada
3.RELIABILTY— IS THE DATA THAT IS COLLECTED RELIABLE ACROSS APPLICATIONS WITHIN THE CLASSROOM, SCHOOL, AND DISTRICT?
Like validity, the term
reliability has been used
for many years to describe
an essential characteristic
of sound assessment.
WHAT IS A
RELIABLE SCORE?
RELIABILITY
Concerned with the
consistency , stability
and dependability of
the scores.
FREE FROM BIAS AND DISTORTION THE ASSESSMENT IS. TEACHERS MIGHT ASK THEMSELVES:
Do I have enough
information about the
learning of this
particular student to
make a definitive
statement?
• WAS THE INFORMATION COLLECTED IN A WAY THAT GIVES ALL STUDENTS AN EQUALCHANCE TO SHOW THEIR LEARNING?
Would another
teacher arrive at the
same conclusion?
Would I make the same
decision if I considered
this information at
another time or in
another way?
ESTIMATES OF RELIABILITY?
1.MEASURE OF STABILITY OR RETEST
Test-retest reliability is
usually measured by
computing the correlation
coefficient between scores of
two administrations.
2.MEASURE OF EQUIVALENCE
The equivalent form of estimate
reliability obtained by giving two
forms of a test to the same group of
individuals on the same day and
correlating the result.
Advantages
• Eliminates the problem of memory effect.
• Reactivity effects (i.e., experience of taking
the test) are also partially controlled.
• Can address a wider array of sampling of the
entire domain than the test-retest method
Possible Disadvantages
• Are the two forms of the test
actually measuring the same thing.
• More Expensive
• Requires additional work to develop
two measurement tools.
3.MEASURE OF INTERNAL
CONSISTENCY• Measures the reliability of a test
solely on the number of items on the test and the inter-correlation among the items. Therefore, it compares each item to every other item.
• If a scale is measuring a construct, then overall the items on that scale should be highly correlated with one another.
• There are two common ways of
measuring internal consistency
1. Cronbach’s Alpha:
.80 to .95(Excellent)
.70 to .80 (Very Good)
.60 to .70 (Satisfactory)
<.60 (Suspect)
2. Item-Total Correlations -
the correlation of the item
with the remainder of the
items (.30 is the minimum
acceptable item-total
correlation).
Split Half - refers to
determining a correlation
between the first half of the
measurement and the
second half of the
measurement (i.e., we
would expect answers to
the first half to be similar to
the second half).
Possible Advantages
• Simplest method - easy to perform
• Time and Cost Effective
Possible Disadvantages
• Many was of splitting
• Each split yields a somewhat different reliability
estimate
• Which is the real reliability of the test?
FACTORS AFFECTING RELIABILITY
• Poor or unclear directions given during administration or inaccurate scoring can affect reliability.
For Example - say you were told that your scores on being social determined your promotion. The result is more likely to be what you think they want than what your behavior is.
• The larger the number of items, the greater
the chance for high reliability.
For Example -it makes sense when you
ponder that twenty questions on your
leadership style is more likely to get a
consistent result than four questions.
• Remedy: Use longer tests or accumulate
scores from short tests.
For Example -If you took an instrument in
August when you had a terrible flu and
then in December when you were feeling
quite good, we might see a difference in
your response consistency. If you were
under considerable stress of some sort or
if you were interrupted while answering
the instrument questions, you might give
different responses.
• The shorter the time, the greater the chance for high
reliability correlation coefficients.
• As we have experiences, we tend to adjust our views a
little from time to time. Therefore, the time interval
between the first time we took an instrument and the
second time is really an "experience" interval.
• Experience happens, and it influences how we see things.
Because internal consistency has no time lapse, one can
expect it to have the highest reliability correlation
coefficient.
THANK YOU