2. RELIABILITY
Reliability is the consistency of a measure. A
measure is said to have a high reliability if it
produces similar results under consistent
conditions
3. THE RELIABILITY COEFFICIENT
1. TEST-RETEST
2. PARALLEL-
FORM
3. SPLIT-HALF
4. INTERNAL
CONSISTENCY
4 methods of
estimating test
reliability coefficient
4. 1. TEST-RETEST
It directly assesses the degree to which test
scores are consistent from one test
administration to the next.
2. PARALLEL-
FORM
The key to this method is the development
of alternate test forms that are equivalent
in terms of content, response processes
and statistical characteristics.
5. 3. SPLIT-HALF
This method treats the two halves of a
measure as alternate forms
4. INTERNAL
CONSISTENCY
It assesses the consistency of results across
items within a test.
6. The goal of estimating reliability is to determine how
much of the variability in test scores is due to standard
errors of measurement and how much is due to
variability in true scores
Standard errors of
measurement is used to
estimate a band or interval
within which a person’s true
score would fall
A true score is the replicable
feature of the concept being
measured.
7. HOW TO MAKE TESTS MORE RELIABLE
The performance
of candidates
The reliability of
the scoring
Take enough samples of
behaviour.
Exclude items which do not
discriminate well between
weaker and stronger students.
Don’t allow candidates too
much freedom.
Write unumbiguous items.
Make candidates familiar with
format & testing techniques, etc.
Use items that permit scoring
which is as objective as possible.
Provide a detailed scoring key.
Train scorers
Agree acceptable responses
and appropriate scores at outset
of scoring.
Identify candidates by
number, not name.
Employ multiple, independent
scoring.
8. FACTORS THAT AFFECT THE RELIABILITY
Administrator factors
Number of items on the instrument
The instrument taker
Heterogeneity of the items
Heterogeneity of the group members
Leght of time between test and retest
