Reliability relates to the consistency and stability of test results. A test is considered reliable if it produces similar outcomes under consistent conditions. There are different types of reliability: internal reliability assesses consistency between items on a test, and external reliability assesses consistency of results over time. Common methods to measure reliability include split-half methods, test-retest methods, and measuring inter-rater reliability between different evaluators. Reliable tests consistently measure the intended construct and produce stable results over time.

1. Reliability of Tests
Saleha Jabeen
GCUF

2. Reliability relates to generalisability,
consistency and stability of tests.
As a linguist Huges describes that
if a test is not reliable, it cant be valid.

3. Test Reliability
A test is said to have a high
reliability, if it produces
similar results Under
consistent conditions

4. Reliability

5. Reliability of Colors

6. Example of reliability
- Measurement of people’s weight and height often results
reliable
- If a language test gives same result by conducting many
times contains high reliability
- Checking tests of a medicine gives same results on
every experiment

7. Types of Reliability
Internal reliability: Assesses the consistency of results
in items within a test.
External reliability: Assesses the consistency of results
conducted at different time
intervals.

8. Methods of Reliability
1- The Split Half method.
Measures the internal consistency
by questionnaires and division
of portions of questions into even
odd numbers.

9. Example
Using the split 12 the sum of the scores for the
odd question as shown in Figure . Determine
whether the test is reliable by students take a
test with 50 questions. For each student the
total score is recorded along with the sum of
the scores for the even questions and
Split-half methodology

11. 2- Test Retest Methodology
Assesses the consistency of result if a test
conducted on different times, it will expect
to give similar result.

12. 3- The Inter Rater Reliability.
If different raters give consistent results to any test
on a relevant sequence, it is called inter rater
reliability.
Example
Some judges gives similar marks to
performers in a reality show, so in that way
they will give a consistent result.

13. The End